CN103973373A - Compression digital pulse interval modulation technology of wireless optical communication system - Google Patents
Compression digital pulse interval modulation technology of wireless optical communication system Download PDFInfo
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- CN103973373A CN103973373A CN201410180619.5A CN201410180619A CN103973373A CN 103973373 A CN103973373 A CN 103973373A CN 201410180619 A CN201410180619 A CN 201410180619A CN 103973373 A CN103973373 A CN 103973373A
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- free timeslot
- interval modulation
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Abstract
In order to reduce intersymbol interference caused by factors of atmosphere turbulence, multipath dispersion effects and the like on atmosphere optical communication and improve the efficiency and reliability of information transmission of a wireless optical communication system, the invention discloses a compression digital pulse interval modulation method. Under the condition of the same bit resolution 4, the transmitting power of a compression digital pulse interval modulation manner is lower than that of fixed length digital pulse interval modulation by 23 percent, the bandwidth utilization rate is higher than that of digital pulse interval modulation by 72 percent, the transmission capacity is higher than that of on-off keying by 67 percent, and self-correction can be performed on received error codes effectively with the compression digital pulse interval modulation manner. Due to the fact that symbol synchronization is not needed, the achieving difficulty of the system is relatively lowered.
Description
Technical field
The present invention relates to a kind of radio optical communication system compressed digital pulse spacing modulation (CDPIM-Compressed Digital Pulse Interval Modulation) method.
Background technology
Wireless light communication generally adopts intensity modulated/direct-detection system, and its main modulation system is on-off keying, pulse position modulation, digit pulse interval modulation and fixed length digit pulse interval modulation.On-off keying mode realizes simply, but power efficiency is lower; Pulse position modulation greatly reduces average transmit power, has but increased system bandwidth demand, also needs slot synchronization and sign synchronization at receiving terminal simultaneously, has increased the difficulty that system realizes; Digit pulse interval modulation has reduced system bandwidth demand to a certain extent, but the unnecessary free timeslot of this modulation system is still more, and the band efficiency of system is lower, and transmission speed is slower; The code length of fixed length digit pulse interval modulation is fixed, and is conducive to receiving terminal demodulation, but the band efficiency of system and transmission capacity are lower, and the error rate is higher.
Atmospheric optical communication is owing to being subject to atmospheric turbulance, scattering and absorption, and the factors such as multipath effect affect, and the error rate of atmospheric optical communication can sharply increase.In order efficiently, reliably to carry out communication, need the band efficiency of modulation-demodulation technique high on the one hand, channel capacity occupancy, transmission Packet Error Ratio and average transmit power are low.Need on the other hand modulation-demodulation technique to there is certain self-correction ability.Therefore adopted in the present invention and there is lower transmitting power, higher band efficiency and transmission capacity, and can carry out to the wrong code character receiving the compressed digital pulse spacing modulation technique of effective self-correction.
Summary of the invention
The electrooptic modulation characteristic of this invention based on lithium columbate crystal, is added in lithium columbate crystal both end voltage signal by modulation the super continuous spectrums luminous flux by lithium columbate crystal is carried out to linear modulation.Modulation signal is to adopt compressed digital pulse spacing modulation technique based on FPGA, carries out signal amplification afterwards through special lithium columbate crystal drive circuit, is then directly added in lithium columbate crystal two ends.In order efficiently, reliably to carry out communication, invented having lower transmitting power, higher band efficiency and transmission capacity, and can carry out to the wrong code character receiving the compressed digital pulse spacing modulation technique of effective self-correction.
The initial time of compressed digital pulse spacing modulation system is high impulse, after add a protection empty slot, then the dope vector of order of modulation constraint is carried out to compressed encoding.First be 4 to divide into groups to information bit according to order of modulation, and the free timeslot number that decimal system numerical value corresponding to each array is comprised judge, if free timeslot numerical value is to be more than or equal to 4 and be less than 8, by this part free timeslot boil down to 01; If judge, free timeslot numerical value is to be greater than 8, by this part free timeslot boil down to 10, whether judgement is simultaneously removed after 8 free timeslots remaining free timeslot number and is met and be more than or equal to 4 and be less than 8, if satisfied boil down to 01, if being still, this part free timeslot number is greater than 8, by this part free timeslot boil down to 10, otherwise, remaining free timeslot is retained, normally carry out modulating-coding.
Compressed digital pulse spacing modulation system is before 5 in order of modulation, normalization transmitting power is all less than modulation systems such as pulse position modulation, digit pulse interval modulation, fixed length digit pulse intervals, this is because in the time of transmission same-code amount of information, the contained high impulse quantity of compressed digital pulse spacing modulator approach other several modulator approaches that compare are little, and the transmitting power needing is like this relatively little; After order of modulation is greater than 5, the modulation systems such as compressed digital pulse spacing modulation system and pulse position modulation, digit pulse interval modulation, fixed length digit pulse interval are more or less the same.This is that the code length of the modulation systems such as pulse position modulation, digit pulse interval modulation, fixed length digit pulse interval can become greatly due to after order of modulation is greater than 5, and the high impulse number comprising also can increase (seeing Figure of description 1).
Be before 5 in order of modulation, compressed digital pulse spacing modulation system is higher than the band efficiency of the modulation systems such as pulse position modulation, digit pulse interval modulation, fixed length digit pulse interval.Along with the increase of order of modulation, the band efficiency of compressed digital pulse spacing modulation system and other several modulation systems all decrease (seeing Figure of description 2).
Be before 4 in order of modulation, there is higher transmission capacity (seeing Figure of description 3) than on-off keying, pulse position modulation, digit pulse interval modulation, fixed length digit pulse interval.
Brief description of the drawings
Fig. 1 is normalization transmitting power contrast of the present invention
Fig. 2 is normalization band efficiency contrast of the present invention
Fig. 3 is transmission capacity comparison of the present invention
Fig. 4 is compressed digital pulse spacing modulating-coding flow chart of the present invention
Fig. 5 is compressed digital pulse spacing modulation /demodulation flow chart of the present invention.
Claims (1)
1. radio optical communication system compressed digital pulse spacing modulation (CDPIM-Compressed Digital Pulse Interval Modulation) technology, it is the wireless light communication method based on pulse position modulation (PPM) transmission information, it is characterized in that: the initial time of compressed digital pulse spacing modulation system is high impulse, after add a protection empty slot, then the dope vector of order of modulation constraint is carried out to compressed encoding; First be 4 to divide into groups to information bit according to order of modulation, and the free timeslot number that decimal system numerical value corresponding to each array is comprised judge, if free timeslot numerical value is to be more than or equal to 4 and be less than 8, by this part free timeslot boil down to 01; If judge, free timeslot numerical value is to be greater than 8, by this part free timeslot boil down to 10, whether judgement is simultaneously removed after 8 free timeslots remaining free timeslot number and is met and be more than or equal to 4 and be less than 8, if satisfied boil down to 01, if being still, this part free timeslot number is greater than 8, by this part free timeslot boil down to 10, otherwise, remaining free timeslot is retained, normally carry out modulating-coding.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410180619.5A CN103973373A (en) | 2014-05-04 | 2014-05-04 | Compression digital pulse interval modulation technology of wireless optical communication system |
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| CN201410180619.5A CN103973373A (en) | 2014-05-04 | 2014-05-04 | Compression digital pulse interval modulation technology of wireless optical communication system |
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| CN103973373A true CN103973373A (en) | 2014-08-06 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112367123A (en) * | 2020-11-10 | 2021-02-12 | 兰州理工大学 | Light space-time keying modulation method suitable for turbulent flow channel |
| WO2023279924A1 (en) * | 2021-07-09 | 2023-01-12 | 华为技术有限公司 | Transmission method and apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101488804A (en) * | 2009-01-04 | 2009-07-22 | 程刚 | Double wide pulse position modulation method for wireless light communication |
| US20110182325A1 (en) * | 2006-03-21 | 2011-07-28 | Commissariat A L'energie Atomique | Space-time coding/decoding method for a dual-antenna pulse uwb communication system |
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2014
- 2014-05-04 CN CN201410180619.5A patent/CN103973373A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110182325A1 (en) * | 2006-03-21 | 2011-07-28 | Commissariat A L'energie Atomique | Space-time coding/decoding method for a dual-antenna pulse uwb communication system |
| CN101488804A (en) * | 2009-01-04 | 2009-07-22 | 程刚 | Double wide pulse position modulation method for wireless light communication |
Non-Patent Citations (1)
| Title |
|---|
| 张亚洲，李智: "大气激光通信中压缩数字脉冲间隔调制技术", 《电讯技术》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112367123A (en) * | 2020-11-10 | 2021-02-12 | 兰州理工大学 | Light space-time keying modulation method suitable for turbulent flow channel |
| CN112367123B (en) * | 2020-11-10 | 2022-08-12 | 兰州理工大学 | Light space-time keying modulation method suitable for turbulent flow channel |
| WO2023279924A1 (en) * | 2021-07-09 | 2023-01-12 | 华为技术有限公司 | Transmission method and apparatus |
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Application publication date: 20140806 |