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Wang H.,Chinese Naval Aeronautical Engineering Academy | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | Song B.,Chinese Naval Aeronautical Engineering Academy | Song B.,Key Laboratory of Shandong Province on Signal and Information Processing | And 3 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2016

Beam spreading is an important effect when a beam propagates in atmospheric turbulence. The collimated Gaussian beam spreading experiments are carried out with beam dynamic change test system under the sea surface environment in Yantai region, and the beam spreading characteristics are analyzed based on data including beam spreading, temperature, relative humidity and atmospheric refractive index structure parameter in different distances and different time periods experiments. Results show that the correlation between beam spreading and refractive index structure parameter is better in sunny weather than in stormy waves weather. But in stormy waves weather the correlation between beam spreading and temperature and relative humidity is good at certain time. In the condition of the same link distance, the beam spreading is obviously smaller at night than in day, and the amplitude fluctuation of beam spreading has the same results. © 2016, Chinese Lasers Press. All right reserved.


Li J.,Yantai Naval Aeronautical and Astronautical University | Liu X.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | Wu X.,Yantai Naval Aeronautical and Astronautical University
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

An improved time division multiplexing network method is proposed to solve such problems as the long queuing delay time, the low link utilization ratio and the non-ideal network throughput which are caused by the increased nodes when time division multiplexing (TDM) technology is used in the ultraviolet communication network at present. Based on the model of ultraviolet communication vertical transceiver, this method selectes the central node to radio into the adjacent cell by taking weighted algorithm of power factor into consideration, and distributes the adjacent cell different slot sections by using piecewise slot method to achieve the goal that the nodes in the far area can use time slot repeatedly and the contradiction between the increased nodes and the limited time slot can be solved. The simulation analysis indicates that, compared with TDM, when the network node number is 40, this method can decline 4 ms in the queuing delay time, raise 2.7% in the link utilization ratio, and increase 1800 bit/s in the channel throughput. ©, 2014, Science Press. All right reserved.


Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | And 4 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2015

Optical intensity signal fading caused by the atmospheric turbulence can severely impact the performance of free space optical communication systems. Large aperture scintillometer is used to test the turbulence effect over the road and sea surface environment. Based on the obtained refractive index structure constant, fading characteristics of free space optical communications are analyzed over these two different environments. The difference of refractive index structure constant under the road environment and the sea environment is analyzed, the result shows that the turbulence intensity of road environment is much stronger than the intensity of sea environment. The change characteristics of probability of fade of colimated Gaussian beam are studied under the two environments, when the scintillation indices are minimum, mean, and maximum, respectively. It shows that the degree of optical signal fading over road is more serious than the degree over sea environment. Fade threshold parameter is discussed when the probability of fade is 10-6. ©, 2015, Science Press. All right reserved.


Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2016

Beam wander is an important effect when a beam propagates in atmospheric turbulence. Based on the marine atmospheric refractive index fluctuation power spectrum, a new theoretical expression is developed for a horizontal propagation path in maritime atmospheric environment. In order to validate the model, a set of measurements of beam wander for a collimated Gaussian beam is carried out using CCD technique during multiple laser transmissions under the sea surface environment in Yantai region, and the experiments are conducted at different time and various ranges. By comparing the theoretical value with measured value under the weak fluctuation condition, the results show that the relative errors between them are below 16%, and the estimation given by the new theoretical expression generally provides a good fit with the data. According to the conclusion of this paper, the beam wander in the maritime atmospheric turbulence can be more accurately predicted. © 2016, Chinese Laser Press. All right reserved.


Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2013

Visibility is a crucial factor of affecting link performance in free space optical (FSO) communication. The bit-error rate (BER) model which does not consider the effect of turbulence is built. On this basis, the affect of receiving aperture on BER under different visibilities is studied by combing the actual visibility data and using the method of simulation. The results show that there are many differences between receiving aperture and BER under different visibilities. If the visibility is high, the BER is much lower, and the performance of system is better. The improvement of the receiving aperture on BER is obvious. At the same time, combining the requirement for BER in engineering practice, the choice of appropriate receiving aperture is discussed under different visibilities, which provides valuable theoretical reference for building the FSO communication link.


Hu H.,Yantai Naval Aeronautical and Astronautical University | Hu H.,Key Laboratory of Shandong Province on Signal and Information Processing | Wang H.-X.,Yantai Naval Aeronautical and Astronautical University | Wang H.-X.,Key Laboratory of Shandong Province on Signal and Information Processing | And 5 more authors.
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2011

To solve the problem of poor validity for pulse position modulation (PPM) combined with ordinary error correction coding, after PPM symbol structure and atmospheric optical wireless communication channel characteristics are investigated, the Turbo product coded (TPC)-PPM mechanism is proposed in this paper which has good anti-fading ability and power efficiency. The bit interleaving of TPC-PPM to break up burst errors is studied, and the soft demodulation confidence measurement algorithm of PPM for soft input soft output (SISO) iterative decoding is also derived. Simulations under weak turbulence show that the TPC-PPM can provide 3 dB gain or more compared with the matched RS coded 3-PPM, and its codeword and modulation level don't need special configuration. Moreover, by appropriately interleaving transmission design between encoder and modulator, the TPC-PPM can acquire better performance without additional cost. The TPC-PPM provides a good solution for atmospheric optical wireless communication system on integrating error control coding with digital pulse modulation.


Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | And 2 more authors.
Applied Optics | Year: 2015

Fog and haze can lead to changes in extinction characteristics. Therefore, the performance of the free space optical link is highly influenced by severe weather conditions. Considering the influential behavior of weather conditions, a state-of-the-art solution for the observation of fog and haze over the sea surface is presented in this paper. A Mie scattering laser radar, with a wavelength of 532 nm, is used to observe the weather conditions of the sea surface environment. The horizontal extinction coefficients and visibilities are obtained from the observation data, and the results are presented in the paper. The changes in the characteristics of extinction coefficients and visibilities are analyzed based on both the short-term (6 days) severe weather data and long-term (6 months) data. Finally, the availability performance of the free space optical communication link is evaluated under the sea surface environment. © 2015 Optical Society of America.


Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | Song B.,Yantai Naval Aeronautical and Astronautical University | Song B.,Key Laboratory of Shandong Province on Signal and Information Processing | And 4 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2016

An atmosphere channel testing link is set up in the marine environment, and the experimental data are tested, including the atmosphere refractive configuration index, the variance of beam drifting and the beam radius. The comparison of free space optics bit error rate (BER) model with none of pointing error and the one with pointing error is carried on. Based on the BER model with pointing error, the BER performance of free space optics system is estimated with the refractive configuration index, beam drifting and beam spreading. Experimental results show that the actual measured BER increases with the atmosphere refractive configuration index. When the atmosphere refractive configuration index is small, the actual measured BER is larger 10 to 20 orders of magnitude than the theoretical calculated BER on account of the effect of beam drifting and beam spreading. © 2016, Chinese Lasers Press. All right reserved.


Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2015

Beam wander is an important effect when a beam propagates in atmospheric turbulence. A set of measurements of beam wander of collimated beam using CCD techniques are conducted under the sea surface environment in Yantai region, and the characteristics are analyzed based on the measured data. Results show that the beam wander is larger in the horizontal direction than in the vertical direction, and the amplitude in horizontal direction is between 5.25 mm and 10.69 mm, and in vertical varies from 4.45 mm to 8.59 mm for a 1.21 km optical path. The mean ratio between the standard deviation in two directions is 1.33, and is lower than the value in other environments. The difference between the beam wander in two directions reduces with the increasing propagation distance, and the ratio is larger in nigthttime than in daytime. The beam wander keeps stable at different times. In addition, atmospheric refractive index structure parameter is also analyzed during the test period. © 2015, Chinese Laser Press. All right reserved.


Wu X.,Yantai Naval Aeronautical and Astronautical University | Wu X.,Key Laboratory of Shandong Province on Signal and Information Processing | Wang H.,Yantai Naval Aeronautical and Astronautical University | Wang H.,Key Laboratory of Shandong Province on Signal and Information Processing | And 4 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2015

Atmospheric refractive index structure parameter (Cn2) is one of the impotant physical quantities measuring the degree of turbulence. The refractive index structure parameter under the sea surface environment in Yantai region from January to June in 2014 is measured by using a large aperture scintillometer. The statistical properties of measured data are analyzed, including frequency count, daily variation and monthly variation. The change characteristics of Cn2 under the sea surface are compared with other environments. The comparative analysis result reveals that the value of Cn2 varies between 10-17 m-2/3 to 10-14 m-2/3 under the sea surface environment, which is classified as medium and weak turbulence. The Cn2at different times are not presented the variable characteristics of"conversion time", and there are no significant differences between Cn2 in the daytime and Cn2 at night. The daily mean vary between 10-16 m-2/3 to 10-14 m-2/3. At the same time, the discrete degree of Cn2 is analyzed combing standard deviation. ©, 2015, Chinese Optical Society. All right reserved.

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