A new method called joint Matched Filter (MF) combining and turbo equalization is proposed for wireless communications over Inter-Symbol Interference (ISI) channels with diversity reception. This method takes diversit...A new method called joint Matched Filter (MF) combining and turbo equalization is proposed for wireless communications over Inter-Symbol Interference (ISI) channels with diversity reception. This method takes diversity combining and equalization as integrity and need just one turbo equalizer for all diversity branches. Computer simulations prove that our method can take advantage of turbo equalization and diversity reception to combat fading of wireless channels.展开更多
In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel d...In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fi展开更多
The principle of band-limited space optical communication system using the techniques of space diversity methods and time domain Rake receiver is analyzed. The joint channel equalizer method combining diversity recept...The principle of band-limited space optical communication system using the techniques of space diversity methods and time domain Rake receiver is analyzed. The joint channel equalizer method combining diversity reception and equalization technique is presented in space laser communication. By computer simulation, the bit error rates of noncoherent space optical on-off keying signal using different space diversity methods, Rake reception with different inter-symbol interferences, joint diversity equalizations with different signal noise rates and different channel numbers are analysed. The results identify that joint diversity equalization method can enhance space optical communication performance evidently.展开更多
Diversity reception of multipath Global Navigation Satellte System(GNSS)signals offers a new insight into carrier phase-based high-precision positioning.The focus of this paper is to demonstrate the fading independenc...Diversity reception of multipath Global Navigation Satellte System(GNSS)signals offers a new insight into carrier phase-based high-precision positioning.The focus of this paper is to demonstrate the fading independence between space and frequency diversity GNSS signals.In harsh urban environments,multipath components arrive to the mobile receiver antenna with different phases and Doppler shifts,therefore giving rise to the discontinuity of code and Doppler observations and large tracking errors.In this paper,an empirical model of fading GNSS signals is constructed,including power fluctuations and spread metrics.Based on this model,real BeiDou Navigation Satellite System(BDS)signals from two GNSS dual-frequency antennas are characterized,at both information and signal level.The block processing algorithm is utilized for signal investigation.Results show that:(1)a high proportion of asynchronous loss-of-lock(around 16%)is experienced by observations of diversity signals;and(2)power fluctuations of fading signals are uncorrelated in frequency separated branches unconditionally,yet for space diversity signals the independency exists in dynamic fading channels only.The results above corroborate the significant potential gain of diversity reception,and could be further implemented in researches of diversity combined GNSS parameter estimation in dense fading conditions.展开更多
In digital radio communication, diversity reception can combat flat fadingand adaptive equalization can combat Inter-Symbol Interference (ISI). In this paper, the structureand algorithm of a multi-channel equalizer wi...In digital radio communication, diversity reception can combat flat fadingand adaptive equalization can combat Inter-Symbol Interference (ISI). In this paper, the structureand algorithm of a multi-channel equalizer with combined diversity reception and adaptiveequalization techniques are studied. Because Phase-Looked-Loops (PLL) are embedded in the equalizer,this equalizer is suitable for coherent communication in channels with high phase fluctuation.Monte Carlo simulation is used to test its performance and the results show that a multi-channeldecision-feedback-equalizer has better performance than a single-channeldecision-feedback-equalizer, and the results of processing high-speed digital underwatercommunication signals demonstrate this farther.展开更多
For differential phase shift keying (DPSK) and noncoherent frequency shift keying (NFSK) systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance...For differential phase shift keying (DPSK) and noncoherent frequency shift keying (NFSK) systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance. However, the bit error performance of such systems over Nakagami channels with an arbitrary covariance matrix and real distinct fading parameters has been seldom described in the literature. This paper studies the problem using a generic correlated Nakagami fading model and presents a closed form solution which is used to study the influence of the fading parameters and the signal-to-noise ratio (SNR) distribution ratios among all the branches on the bit error performance. Moreover, the average SNRs of each branch are not restricted to one value in the analysis. The closed form solution developed for the problem can be used to study the influence of the fading parameters and the SNR distribution ratios on the error performance.展开更多
In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effe...In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effective and widely applied technique in wireless communications. The current approach is to use multiple antennas at the receiver in order to improve the quality of the received signal. A method of modeling and simulation is proposed to depict the principle and feasibility of the multiple receiver adopted in UV communication. The study provides an insight to the channel characteristics and achievable capabilities of ultraviolet communication systems with multiple receivers. It provides guidelines for practical system design with discussions on trade off between the receiver gain and the additional cost.展开更多
基金Supported by the National Natural Science Foundation of China (No. 60572176)
文摘A new method called joint Matched Filter (MF) combining and turbo equalization is proposed for wireless communications over Inter-Symbol Interference (ISI) channels with diversity reception. This method takes diversity combining and equalization as integrity and need just one turbo equalizer for all diversity branches. Computer simulations prove that our method can take advantage of turbo equalization and diversity reception to combat fading of wireless channels.
基金This work was supported by the Zhejiang Provincial Natural Science Foundation of China under Grant No. 603127.
文摘In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fi
文摘The principle of band-limited space optical communication system using the techniques of space diversity methods and time domain Rake receiver is analyzed. The joint channel equalizer method combining diversity reception and equalization technique is presented in space laser communication. By computer simulation, the bit error rates of noncoherent space optical on-off keying signal using different space diversity methods, Rake reception with different inter-symbol interferences, joint diversity equalizations with different signal noise rates and different channel numbers are analysed. The results identify that joint diversity equalization method can enhance space optical communication performance evidently.
文摘Diversity reception of multipath Global Navigation Satellte System(GNSS)signals offers a new insight into carrier phase-based high-precision positioning.The focus of this paper is to demonstrate the fading independence between space and frequency diversity GNSS signals.In harsh urban environments,multipath components arrive to the mobile receiver antenna with different phases and Doppler shifts,therefore giving rise to the discontinuity of code and Doppler observations and large tracking errors.In this paper,an empirical model of fading GNSS signals is constructed,including power fluctuations and spread metrics.Based on this model,real BeiDou Navigation Satellite System(BDS)signals from two GNSS dual-frequency antennas are characterized,at both information and signal level.The block processing algorithm is utilized for signal investigation.Results show that:(1)a high proportion of asynchronous loss-of-lock(around 16%)is experienced by observations of diversity signals;and(2)power fluctuations of fading signals are uncorrelated in frequency separated branches unconditionally,yet for space diversity signals the independency exists in dynamic fading channels only.The results above corroborate the significant potential gain of diversity reception,and could be further implemented in researches of diversity combined GNSS parameter estimation in dense fading conditions.
文摘In digital radio communication, diversity reception can combat flat fadingand adaptive equalization can combat Inter-Symbol Interference (ISI). In this paper, the structureand algorithm of a multi-channel equalizer with combined diversity reception and adaptiveequalization techniques are studied. Because Phase-Looked-Loops (PLL) are embedded in the equalizer,this equalizer is suitable for coherent communication in channels with high phase fluctuation.Monte Carlo simulation is used to test its performance and the results show that a multi-channeldecision-feedback-equalizer has better performance than a single-channeldecision-feedback-equalizer, and the results of processing high-speed digital underwatercommunication signals demonstrate this farther.
文摘For differential phase shift keying (DPSK) and noncoherent frequency shift keying (NFSK) systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance. However, the bit error performance of such systems over Nakagami channels with an arbitrary covariance matrix and real distinct fading parameters has been seldom described in the literature. This paper studies the problem using a generic correlated Nakagami fading model and presents a closed form solution which is used to study the influence of the fading parameters and the signal-to-noise ratio (SNR) distribution ratios among all the branches on the bit error performance. Moreover, the average SNRs of each branch are not restricted to one value in the analysis. The closed form solution developed for the problem can be used to study the influence of the fading parameters and the SNR distribution ratios on the error performance.
文摘In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effective and widely applied technique in wireless communications. The current approach is to use multiple antennas at the receiver in order to improve the quality of the received signal. A method of modeling and simulation is proposed to depict the principle and feasibility of the multiple receiver adopted in UV communication. The study provides an insight to the channel characteristics and achievable capabilities of ultraviolet communication systems with multiple receivers. It provides guidelines for practical system design with discussions on trade off between the receiver gain and the additional cost.