This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous w...This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.展开更多
Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Vi...Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Viterbi algorithm(IVA) is derived for a suboptimal ML noncoherent detection.Simulation results show that the IVA can approach the error performances of the exhaustive detection method but at a lower complexity.展开更多
Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of mult...Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) converter.Balancing flying capacitor voltages is an important constraint to the proper performance of FCM and SM converters.Thus,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the converter.This paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM converters.The proposed strategy is based on a discrete time model of the converter and uses only a load current sensor.The circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor voltages.Simplicity is the most significant advantage of the proposed strategy,its performance being based on simple equations.展开更多
文摘This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.
基金supported by the National Natural Science Foundation of China(61302095,61401165)the Natural Science Foundation of Fujian Province of China(2014J01243,2014J05076,2015J01262)the Huaqiao University Science Foundation(13Y0384)
文摘Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Viterbi algorithm(IVA) is derived for a suboptimal ML noncoherent detection.Simulation results show that the IVA can approach the error performances of the exhaustive detection method but at a lower complexity.
文摘Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) converter.Balancing flying capacitor voltages is an important constraint to the proper performance of FCM and SM converters.Thus,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the converter.This paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM converters.The proposed strategy is based on a discrete time model of the converter and uses only a load current sensor.The circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor voltages.Simplicity is the most significant advantage of the proposed strategy,its performance being based on simple equations.
