CN104753595A - Modulation method supporting brightness modulation of indoor visible light communication system - Google Patents
Modulation method supporting brightness modulation of indoor visible light communication system Download PDFInfo
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Abstract
The invention discloses a modulation method supporting brightness modulation of an indoor visible light communication system; aiming at the requirement that the visible light communication gives consideration to illumination in actual system, and reliable communication is realized under multiple brightness level conditions and the mixed MPPM modulation method is adopted; different modulation combining schemes are set according to different brightness modulation demands, a receiving terminal judges the ratio of the modulation combination according to the energy detection, and different illumination brightness levels are supported while the reliable transmission for information is ensured. Compared with technical scheme of adopting OOK modulation with redundancy compensation symbol in the standard IEEE802.15.7, and the technical scheme can have obvious performance gain under the indoor optical communication point-to-point communication scene.
Description
Technical field
The present invention relates to the modulator approach supporting brightness regulation in a kind of indoor visible light communication system, belong to visible light communication technology.
Background technology
Visible light communication technology becomes the focus of communications field research in recent years gradually.Visible light communication technology refers to and utilizes the light of visible light wave range as information carrier, does not use the transmission medium of the wire message way such as optical fiber, and the communication mode of direct transmitting optical signal in atmosphere.LED visible light communication is than fluorescent lamp and the fast feature of incandescent lamp switch speed based on visible light emitting diode, utilize taillight before being equipped with the indoor and outdoor large display screen of LED, lighting apparatus, annunciator and automobile etc. to send detect by an unaided eye less than High Speed Modulation light wave signal come modulates information and transmission, then utilize the electrooptical devices such as photodiode receive optical carrier and obtain information.
Optical communication can combine with illuminator, provides the communication of two-forty to meet people at indoor use mobile phone, the demand of the electronic equipments such as notebook computer, simultaneously can energy savings, does not damage human body.Supporting that brightness of illumination regulates is the important consideration of visible light communication about energy efficiency, and when user regulates light source time, communication should maintain.When human eye responds to the light of low-light level, can increase pupil and allow more light to enter, this makes communication system should support a large-scale brightness regulation.Generally have two kinds of methods to carry out the brightness of illumination of control system transmitting terminal: one is change the amplitude sending symbol, two is change to send the number of ' 1 ' and the number of ' 0 ' in symbol sebolic addressing.What standard IEEE 802.15.7 adopted is second method, the symbol fixing certain length in one frame symbol is used for sending OOK (on-off keying amplitude modulation system) modulation symbol, remaining symbol is not used for transmission information, by ' 1 ' and ' 0 ' duty ratio keeping a frame symbol sending certain quantity.Visible, the modulation scheme in standard brings certain redundancy.
Summary of the invention
Goal of the invention: in order to overcome the defect of modulation scheme in existing standard, the invention provides the modulator approach supporting brightness regulation in a kind of indoor visible light communication system, adopt mixing MPPM modulation technique, on the basis supporting brightness regulation, make full use of the redundant symbol of modulation scheme in standard, to provide more excellent bit error rate performance.
Technical scheme: for achieving the above object, the technical solution used in the present invention is:
The modulator approach of brightness regulation is supported in a kind of indoor visible light communication system, at indoor fixed position arrangement LED and receiving equipment, and LED aims at the photodetector of receiving equipment, the peak transmitted power of setting LED is fixed value, by adopting mixing MPPM modulation, blind Detecting technology and MPPM demodulator, realize more excellent bit error rate performance; Described mixing MPPM modulation is specially: for a certain illumination brightness levels, in frame data, partial data adopts n-MPPM modulation, remaining data adopts (n+1)-MPPM to modulate, N-MPPM modulation represents that from M time slot, choose N number of time slot carries out transfer of data, 1≤N<M, represents n or n+1 with N; Specifically comprise the steps:
(1) according in real system to the demand of brightness of illumination control range, Selecting All Parameters M, like this mix MPPM modulation support brightness of illumination scope be
(2) according to selected M, each N-MPPM modulation symbol can represent maximum
the information of bit symbol, supporting under the prerequisite that brightness of illumination scope is identical, the modulation system adopting the efficiency of transmission of mixing MPPM modulation at least to add redundant symbol with OOK modulation is equal;
(3) for a certain illumination brightness levels P, have
then to should illumination brightness levels P, in frame data, the ratio data adopting n-MPPM modulation be a, and the ratio data adopting (n+1)-MPPM to modulate is b, meets: a+b=1, a=1-P × M+n, b=P × M-n; If the length of frame data is L, the symbol after mixing MPPM modulation comprises S mixing MPPM modulation symbol, then should meet S × amodT=0 and S × bmodT=0, T>=100, T>=100, do the symbolic number that primary energy is cumulative when T represents receiving terminal blind Detecting, T is larger, and result is more accurate;
(4) according to the method in step (3), the ratio of often kind of N-MPPM modulation symbol shared by whole mixing MPPM modulation symbol under each illumination brightness levels is calculated; Transmitting terminal is according to current illumination brightness levels, and adopt corresponding mixing MPPM modulation system to modulate, in modulated process, the mapping mode of N-MPPM modulation symbol and bit symbol meets Gray's criterion, to improve the performance of receiving terminal;
(5) adopt interleaver to interweave to the N-MPPM modulation symbol produced after mixing MPPM modulation, sent by transmitting terminal, received by receiving terminal, then adopt deinterleaver to carry out deinterleaving to N-MPPM modulation symbol;
(6) the cumulative of energy is cooked to the every continuous T after a deinterleaving mixing MPPM modulation symbol, if T mix gross energy E that MPPM modulation symbol energy accumulation obtains between
with
between, then what judge the employing of this T mixing MPPM modulation symbol is N-MPPM modulation system, according to the demodulation of N-MPPM modulation system; Wherein e represents the energy of a 1-MPPT modulation symbol.
Beneficial effect: the modulator approach supporting brightness regulation in indoor visible light communication system provided by the invention, relative to prior art, possesses following advantage:
1, modulator approach provided by the invention can make full use of the signal energy of transmitting terminal, and when supporting large-scale brightness regulation, in standard, OOK modulates the scheme adding redundant symbol and can introduce a large amount of redundant symbols, and capacity usage ratio is low;
2, under good communication condition, modulator approach provided by the invention can sacrificial section BER performance, brings higher transmission rate;
3, under identical signal to noise ratio condition, modulator approach provided by the invention and OOK in standard modulate add redundant symbol scheme compared with have more excellent BER performance.
Accompanying drawing explanation
Fig. 1 is realization flow figure of the present invention;
Fig. 2 adopts OOK to modulate the formation schematic diagram adding the frame symbol compensating redundant symbol in IEEE802.15.7 standard;
Fig. 3 is the formation schematic diagram of the frame symbol adopting 1-4PPM modulation and 2-4PPM modulation mixing;
The bit symbol mapping mode that Fig. 4 selects when being and specifically selecting N-4PPM modulation system;
Fig. 5 is when not adding FEC coding, the BER performance comparison of the OOK modulation scheme under 0.35 brightness degree in IEEE 802.15.7 and mixing MPPM modulation scheme;
Fig. 6 is when not adding FEC coding, the BER performance comparison of the OOK modulation scheme under 0.5 brightness degree in IEEE 802.15.7 and mixing MPPM modulation scheme;
Fig. 7 is when not adding FEC coding, the BER performance comparison of the OOK modulation scheme under 0.65 brightness degree in IEEE 802.15.7 and mixing MPPM modulation scheme.
Embodiment
Below in conjunction with accompanying drawing, the present invention is further described.
Be illustrated in figure 1 the modulator approach supporting brightness regulation in a kind of indoor visible light communication system, by making full use of the redundant symbol of modulation scheme in standard, provide more excellent bit error rate performance, while meeting room lighting demand, achieving reliable communication; The method is specially: at indoor fixed position arrangement LED and receiving equipment, and LED aims at the photodetector of receiving equipment, the peak transmitted power of setting LED is fixed value, by adopting mixing MPPM modulation, blind Detecting technology and MPPM demodulator, realizes more excellent bit error rate performance; Described mixing MPPM modulation is specially: for a certain illumination brightness levels, in frame data, partial data adopts n-MPPM modulation, remaining data adopts (n+1)-MPPM to modulate, N-MPPM modulation represents that from M time slot, choose N number of time slot carries out transfer of data, 1≤N<M, represents n or n+1 with N; Concrete modulated process as shown in Figure 1, comprises the steps:
(1) according in real system to the demand of brightness of illumination control range, Selecting All Parameters M, like this mix MPPM modulation support brightness of illumination scope be
select M=4 in this case, then mixing MPPM modulates the scope of the brightness of illumination adjustment that can support is 0.25 ~ 0.75.
(2) according to selected M, each N-4PPM modulation symbol can represent the information of 2 bit symbols, assuming that frame data comprise 1000 bit symbol information, then needs transmission 500 N-MPPM modulation symbols.
For OOK modulation, same frame data, need 1000 time slots to send OOK symbol, need 1000 time slots to send simultaneously and compensate redundant symbol, altogether take 2000 time slots.Adopt mixing MPPM modulation system, 500 N-4PPM modulation symbols are used to take 2000 time slots equally, illumination brightness levels is controlled: when compensation redundant symbol is all ' 0 ' by the number compensating ' 1 ' in redundant symbol, brightness is 0.25, when redundancy compensation symbol is all ' 1 ', brightness is 0.75; When redundancy compensation symbol 50% is ' 1 ', brightness is 0.5; By that analogy.The transmission symbol sebolic addressing adopting the OOK modulation scheme in IEEE 802.15.7 standard as shown in Figure 2, adopts the transmission symbol sebolic addressing of mixing MPPM modulation scheme as shown in Figure 3.
(3) for a certain illumination brightness levels P, have
then to should illumination brightness levels P, in frame data, the ratio data adopting n-MPPM modulation be a, and the ratio data adopting (n+1)-MPPM to modulate is b, meets: a+b=1, a=1-P × M+n, b=P × M-n; If the length of frame data is L, the symbol after mixing MPPM modulation comprises S mixing MPPM modulation symbol, then should meet S × amodT=0 and S × bmodT=0, T>=100.
(4) according to the method in step (3), the ratio of often kind of N-MPPM modulation symbol shared by whole mixing MPPM modulation symbol under each illumination brightness levels is calculated.Luminance difference between using 0.05 as adjacent two illumination brightness levels, 1000 bit symbol information can use 500 mixing MPPM modulation symbols to represent, meet 500 × amod100=0 and 500 × bmod100=0, here T=100, contain 11 illumination brightness levels between such 0.25 to 0.75 altogether, corresponding symbol sebolic addressing composition is as shown in table 1.
The formation of MPPM modulation symbol sequence is mixed under the different brightness degree of table 1
Transmitting terminal, according to current illumination brightness levels, adopts corresponding mixing MPPM modulation system to modulate.For 1-4PPM and 3-4PPM, there are 4 modulation symbols and Hamming distance between them is equal, can natural mapping be adopted; For 2-4PPM, have
individual modulation symbol, therefrom need choose 4 symbols, is used for representing the information of 2 bits.Mapping mode about N-MPPM modulation symbol and bit symbol meets Gray's criterion, and result as shown in Figure 4.
(5) adopt interleaver to interweave to the N-MPPM modulation symbol produced after mixing MPPM modulation, sent by transmitting terminal, received by receiving terminal, then adopt deinterleaver to carry out deinterleaving to N-MPPM modulation symbol.
(6) the cumulative of energy is cooked to every continuous T=100 after a deinterleaving mixing MPPM modulation symbol, if T mix gross energy E that MPPM modulation symbol energy accumulation obtains between
with
between, then what judge the employing of this T mixing MPPM modulation symbol is N-MPPM modulation system, according to the demodulation of N-MPPM modulation system; Wherein e represents the energy of a 1-MPPT modulation symbol.
The simulated BER curves of the OOK modulation scheme in IEEE 802.15.7 and mixing MPPM modulation scheme is as shown in Fig. 5 ~ 7, and the BER curve of two kinds of modulation schemes when Fig. 5 represents that illumination brightness levels is 0.35 is 10 at BER
-4time, adopting mixing MPPM modulation to have the gain of about 2dB compared with the OOK modulation scheme in standard, is 10 at BER
-5time also have the gain of about 2dB, the simulated BER curves of two kinds of different modulation schemes when Fig. 6 and Fig. 7 represents that illumination brightness levels is 0.5 and 0.65, the modulation scheme that visible the present invention proposes has certain performance gain compared with the modulation scheme in standard IEEE 802.15.7.
The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (1)
1. in an indoor visible light communication system, support the modulator approach of brightness regulation, it is characterized in that: at indoor fixed position arrangement LED and receiving equipment, and LED aims at the photodetector of receiving equipment, the peak transmitted power of setting LED is fixed value, by adopting mixing MPPM modulation, blind Detecting technology and MPPM demodulator, realize more excellent bit error rate performance; Described mixing MPPM modulation is specially: for a certain illumination brightness levels, in frame data, partial data adopts n-MPPM modulation, remaining data adopts (n+1)-MPPM to modulate, N-MPPM modulation represents that from M time slot, choose N number of time slot carries out transfer of data, 1≤N<M, represents n or n+1 with N; Specifically comprise the steps:
(1) according in real system to the demand of brightness of illumination control range, Selecting All Parameters M, like this mix MPPM modulation support brightness of illumination scope be
(2) according to selected M, each N-MPPM modulation symbol can represent maximum B=log
2 the information of bit symbol, supporting under the prerequisite that brightness of illumination scope is identical, the modulation system adopting the efficiency of transmission of mixing MPPM modulation at least to add redundant symbol with OOK modulation is equal;
(3) for a certain illumination brightness levels P, have
then to should illumination brightness levels P, in frame data, the ratio data adopting n-MPPM modulation be a, and the ratio data adopting (n+1)-MPPM to modulate is b, meets: a+b=1, a=1-P × M+n, b=P × M-n; If the length of frame data is L, the symbol after mixing MPPM modulation comprises S mixing MPPM modulation symbol, then should meet the symbolic number done primary energy when S × amodT=0 and S × bmodT=0, T>=100, T represent receiving terminal blind Detecting and add up;
(4) according to the method in step (3), the ratio of often kind of N-MPPM modulation symbol shared by whole mixing MPPM modulation symbol under each illumination brightness levels is calculated; Transmitting terminal is according to current illumination brightness levels, and adopt corresponding mixing MPPM modulation system to modulate, in modulated process, the mapping mode of N-MPPM modulation symbol and bit symbol meets Gray's criterion;
(5) adopt interleaver to interweave to the N-MPPM modulation symbol produced after mixing MPPM modulation, sent by transmitting terminal, received by receiving terminal, then adopt deinterleaver to carry out deinterleaving to N-MPPM modulation symbol;
(6) the cumulative of energy is cooked to the every continuous T after a deinterleaving mixing MPPM modulation symbol, if T mix gross energy E that MPPM modulation symbol energy accumulation obtains between
with
between, then what judge the employing of this T mixing MPPM modulation symbol is N-MPPM modulation system, according to the demodulation of N-MPPM modulation system; Wherein e represents the energy of a 1-MPPT modulation symbol.
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| CN106788724A (en) * | 2016-12-09 | 2017-05-31 | 暨南大学 | A kind of visible light communication system and its implementation based on polarization code |
| CN106888056A (en) * | 2017-03-29 | 2017-06-23 | 西安易朴通讯技术有限公司 | The power regulating method and device of visible light communication |
| WO2017124279A1 (en) * | 2016-01-18 | 2017-07-27 | 华为技术有限公司 | Data sending method based on visible light communication and sending end device |
| WO2018041252A1 (en) * | 2016-09-02 | 2018-03-08 | Huawei Technologies Co., Ltd. | Method of dimming for visible light communications |
| CN108366031A (en) * | 2017-08-14 | 2018-08-03 | 广东顺德中山大学卡内基梅隆大学国际联合研究院 | In conjunction with the reversed polarity multi-pulse position modulation optical OFDM system of brightness adjustment control |
| CN111181643A (en) * | 2020-01-06 | 2020-05-19 | 江南大学 | Hybrid visible light communication method based on MPPM dimming control |
| CN112840745A (en) * | 2018-10-18 | 2021-05-25 | 昕诺飞控股有限公司 | Determining light settings and/or daylight blocker settings based on data signal quality |
| WO2022022210A1 (en) * | 2020-07-28 | 2022-02-03 | 华为技术有限公司 | Information transmission method and communication device |
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Cited By (10)
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| WO2017124279A1 (en) * | 2016-01-18 | 2017-07-27 | 华为技术有限公司 | Data sending method based on visible light communication and sending end device |
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| US10298333B2 (en) | 2016-09-02 | 2019-05-21 | Futurewei Technologies, Inc. | Method of dimming for visible light communications |
| CN106788724A (en) * | 2016-12-09 | 2017-05-31 | 暨南大学 | A kind of visible light communication system and its implementation based on polarization code |
| CN106888056A (en) * | 2017-03-29 | 2017-06-23 | 西安易朴通讯技术有限公司 | The power regulating method and device of visible light communication |
| CN108366031A (en) * | 2017-08-14 | 2018-08-03 | 广东顺德中山大学卡内基梅隆大学国际联合研究院 | In conjunction with the reversed polarity multi-pulse position modulation optical OFDM system of brightness adjustment control |
| CN108366031B (en) * | 2017-08-14 | 2021-04-06 | 广东顺德中山大学卡内基梅隆大学国际联合研究院 | Reverse polarity multi-pulse position modulation light OFDM system combined with dimming control |
| CN112840745A (en) * | 2018-10-18 | 2021-05-25 | 昕诺飞控股有限公司 | Determining light settings and/or daylight blocker settings based on data signal quality |
| CN111181643A (en) * | 2020-01-06 | 2020-05-19 | 江南大学 | Hybrid visible light communication method based on MPPM dimming control |
| WO2022022210A1 (en) * | 2020-07-28 | 2022-02-03 | 华为技术有限公司 | Information transmission method and communication device |
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