In order to decrease dispersion penalty and increase the optical bandwidth efficiency,an optical single-side-band modulation(SSBM) scheme in sub-carrier multiplexing(SCM) is proposed.The principle of the SSBM is analy...In order to decrease dispersion penalty and increase the optical bandwidth efficiency,an optical single-side-band modulation(SSBM) scheme in sub-carrier multiplexing(SCM) is proposed.The principle of the SSBM is analytically presented,and a configuration for generating optical SSB signal is proposed using a balanced Mach-Zehnder electro-optic modulator.展开更多
In this paper, the problem of channel estimation for superposition coded modulation-orthogonal frequency division multiplexing (SCM-OFDM) systems over frequency selective channels is investigated. Assuming that the pa...In this paper, the problem of channel estimation for superposition coded modulation-orthogonal frequency division multiplexing (SCM-OFDM) systems over frequency selective channels is investigated. Assuming that the path delays are known, a new channel estimator based on modified Kalman filter algorithms is introduced for the estimation of the multipath Rayleigh channel complex gains (CG). In the simulation, the mean square error (MSE) and bit-error-rate (BER) performances are given to verify the effectiveness of the Kalman estimation algorithms for SCM-OFDM systems.展开更多
基金supported by Science Foundation for Youthful Teachers of Anhui University (Grant No.2007jql104)
文摘In order to decrease dispersion penalty and increase the optical bandwidth efficiency,an optical single-side-band modulation(SSBM) scheme in sub-carrier multiplexing(SCM) is proposed.The principle of the SSBM is analytically presented,and a configuration for generating optical SSB signal is proposed using a balanced Mach-Zehnder electro-optic modulator.
文摘In this paper, the problem of channel estimation for superposition coded modulation-orthogonal frequency division multiplexing (SCM-OFDM) systems over frequency selective channels is investigated. Assuming that the path delays are known, a new channel estimator based on modified Kalman filter algorithms is introduced for the estimation of the multipath Rayleigh channel complex gains (CG). In the simulation, the mean square error (MSE) and bit-error-rate (BER) performances are given to verify the effectiveness of the Kalman estimation algorithms for SCM-OFDM systems.
文摘油田的水下控制模块液压系统长期处于高压、高温和腐蚀性环境下,面临着极高的故障风险。针对液压系统进行有效的故障诊断和预防性维护,研究将基于动态贝叶斯网络(Dynamic Bayesian Network,DBN)构建液压系统的故障诊断模型。实验结果表明,液压系统历史故障概率与实验预测的故障概率值均随时间的增加而增加。在T=0时,预测的液压系统故障概率值为0.106,与历史液压系统故障概率0.117非常接近;在T=20时,预测故障概率为0.194,历史故障概率为0.198,两者的诊断概率差值略有增加。此外,从T=0到T=20,模型故障诊断精确性均在85%以上,其中在T=0时的模型预测精确度最高为96.2%,T=20时,模型预测精确度最低为85.7%。研究表明,所提出的诊断模型在故障诊断时具有较好的精确性和稳定性,为油田水下控制模块(Subsea Control Module,SCM)液压系统的智能故障诊断提供一种新的解决方案。
