一种基于D8PSK／ASK正交调制的新型光标记方案研究

深入研究了差分八相移键控（I）8PSK）j幅移键控（AsK）正交调制格式的机理,提出了一种基于D8PsKjASK正交调制的新型光标记方案,利用D8PSK作为载荷的调制方式,ASK作为标记的调制方式,仿真实现了载荷120Gb／s、标记10Gb／s的传输速率。分析了信号的消光比（ER）对误码率（BER）的影响,仿真结果表明...     

一种具有LPI特性的雷达信号一新的FSK/PSK信号

探讨了一种由ＦＳＫ信号和ＰＳＫ信号组合而成的新的ＦＳＫ／ＰＳＫ雷达信号。理论分析了和计算机模拟了该类信号的模糊函数（图），距离分辨率、速度分辨率和低截获性能。分析表明了该类信号在高分辨和低截获方面的有效性。     

Parameter Estimation Approach of FSK/PSK Radar Signal

A parameter estimation approach of reconnaissance hybrid radar signal combined frequency-shift keying(FSK) and phase-shift keying(PSK) is presented.Firstly,the multi-phase difference is adopted to calculate the instantaneous frequency(IF) of FSK/PSK,then the frequency points of FSK are estimated from the histogram of IF.The code rate of PSK is extracted from the locations of phase discontinuity.Finally,the multi-phase difference of the square of the received signal is computed to estimate the code rate of FSK.The presented algorithm has higher accuracy of parameter estimation when the signal-to-noise ratio(SNR) is above 11 dB.     

Optical DPSK demodulator based on /spl pi/-phase-shifted fiber Bragg grating with an optically tunable phase shifter

We propose and demonstrate a novel optical differential phase-shift keying (DPSK) demodulator with an optically tunable phase shifter. The proposed DPSK demodulator is implemented by using a /spl pi/-phase-shifted fiber Bragg grating and an Yb/sup 3+/-Al/sup 3+/ codoped optical fiber. A 10-Gb/s DPSK signal was successfully demodulated by the proposed demodulator, showing clearly open eye diagrams as well as bit-error-free performance. Moreover, the phase of delayed optical signal can be tuned by the phase shifter that is controlled by a pumping light at around 980nm.     

All-optical modulation format conversion from PSK to ASK based on phase-sensitive amplification

With the development of the optics communication system and optical signal modulation technology, the amplitude-shift keying (ASK) and phase-shift keying (PSK) are both used in different optical communication sub-networks. In this paper, a novel all-optical modulation format from PSK to ASK based on phase-sensitive amplification is proposed and demonstrated. Using the nonlinear interference of the single-pump phase-sensitive amplification, the signal wavelength can be preserved while the modulation format is conversed. The proposed scheme provides the flexible intermediate node interface transformation in future optical networks.     

A novel orthogonal modulation format of D8PSK/ASK with differential bi-phase encoding and its application in a label switching optical network

The principle of a novel orthogonal modulation format of differential 8-level phase-shift keying amplitude-shift keying (D8PSK/ASK) with differential bi-phase encoding (DBC) is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results are compared with other current schemes, and the effects of transmission range, modulation extinction ratio (ER) and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate (BER) are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.     

Comparison of 112-Gb/s PM-RZ-DQPSK and PM-RZ-D8PSK in Terms of OSNR Requirement and Transmission Impairments

We have, for the first time, experimentally investigated 112-Gb/s polarization-multiplexed return-to-zero differential 8-ary phase-shift keying (PM-RZ-D8PSK) with differential detection in terms of optical signal-to-noise ratio requirement, group velocity dispersion (GVD), and differential group delay (DGD) tolerances, together with a direct comparison with PM-RZ differential quadrature phase-shift keying at equivalent bit rate. The results indicate higher tolerances with respect to GVD and DGD but lower receiver sensitivity in the case of PM-RZ-D8PSK.      

Hybrid Access Network Integrated With Wireless Multilevel Vector and Wired Baseband Signals Using Frequency Doubling and No Optical Filtering

This letter experimentally demonstrated a hybrid access network which supports both radio-over-fiber and fiber-to-the-x systems. A 20-GHz radio-frequency (RF) 312.5-MSymbol/s M-ary phase-shift keying (PSK) signal and a baseband (BB) 1.25-Gb/s on–off keying signal are simultaneously generated and transmitted over an identical distributed infrastructure. The wired BB signal is compatible with the existing passive optical network (PON) system, and the wireless RF PSK signal can also share the same distributed infrastructure. The proposed system has no RF fading issue, no narrowband optical filter at remote node to separate the RF and BB signals, and can carry vector signals. Moreover, a frequency doubling for optical RF signal generation is achieved to reduce the bandwidth requirement of the transmitter. After transmission over 25-km standard signal-mode fiber, the receiver sensitivity penalties are less than 0.5 dB for both the RF and BB channels.      

Low-Complexity Compensation of SOA Nonlinearity for Single-Channel PSK and OOK

Carrier density fluctuations in semiconductor optical amplifiers (SOAs) impose penalties on phase-shift keying (PSK) signals due to nonlinear phase noise (NLPN), and on-off keying (OOK) signals due to self-gain modulation. In this paper, we propose a simple scheme to equalize the impairments induced by SOA nonlinearities, derived from the small signal analysis of carrier density fluctuations. We demonstrate via simulation almost complete cancelation of the NLPN added by a saturated SOA on a differential PSK signal. We demonstrate via both simulations and experiment the effectiveness of the method for mitigation of nonlinear distortions imposed by SOAs on an OOK signal.      

Effects of chromatic dispersion on optical coherent-detection systems

Chromatic dispersion induces to a phase-modulated optical signal a constand phase rotation that was never included in most previous studies. When the constant phase shift is removed by a phase-locked loop, the dispersion tolerance of a coherent-detection system is increased. The dispersion tolerance of phase-shift keying (PSK) signal is compared with differential PSK (DPSK) signals by numerical simulation and experimental measurement. Contrary to conventional belief, PSK signal has larger dispersion tolerance than DPSK signal.     

An asymptotic optimal algorithm for modulation classification

A suboptimal algorithm for modulation classification was proposed for classifying the modulation type of general M-ary phase-shifted keying (MPSK) signals. Yang and Soliman (see IEEE Trans. Aerosp. Electron. Syst., vol.33, no.1, p.38-45, 1997) approximated the phase probability density function of a received signal to be the Tikhonov function. Instead, we employ the exact phase density function and derive an asymptotic optimal classification algorithm. We show a structure of this proposed classifier for continuous wave (CW), binary phase-shift keying (BPSK), quaternary phase-shift keying (QPSK), and 8PSK. Besides, we give an example to demonstrate the capability of this algorithm and compare its performance to that in Yang and Soliman. It is shown that the performance is more effective     

WDM PON using 10-Gb/s DPSK downstream and re-modulated 10-Gb/s OOK upstream based on SOA

A signal remodulation scheme of 10-Gb/s differential phase-shift keying(DPSK) downstream and 10-Gb/s on-off keying(OOK) upstream using a semiconductor optical amplifier(SOA) and a Mach-Zehnder intensity modulator(MZ-IM) at the optical networking unit(ONU) side for wavelength division multiplexed passive optical network(WDM PON) is proposed.Simulation results indicate that error-free operation can be achieved in a 20-km transmission,and the receiver sensitivity of return-to-zero differential phase-shift keying(RZ-DPSK) is higher than nonreturn-to-zero differential phase-shift keying(NRZ-DPSK) in the proposed scheme.     

NRZ-OOK-to-RZ-BPSK modulation-format conversion using SOA-MZI wavelength converter

A novel all-optical modulation-format conversion from nonreturn-to-zero on-off keying (NRZ-OOK) to return-to-zero binary phase-shift keying (RZ-BPSK) is proposed. A Mach-Zehnder interferometric (MZI) wavelength converter consisting of integrated semiconductor optical amplifiers (SOAs) is utilized to implement the proposed format conversion. Error-free operation at a bit rate of 10.7 Gb/s is experimentally demonstrated in order to show the feasibility of the proposed scheme. The received sensitivity of the converted signal is improved by 2.9 dB compared with a back-to-back NRZ-OOK signal at BER=10/sup -9/. In addition, a reasonable dispersion tolerance of the converted signal up to /spl plusmn/500 ps/nm is observed. The numerical simulation based upon the carrier-rate equation verifies the experimental results.     

Gilbert-Varshamov bound for Euclidean space codes overdistance-uniform signal sets

In this correspondence, in an extension of Piret's bound for codes over phase-shift keying (PSK) signal sets, we investigate the application of the Gilbert-Varshamov (GV) bound to a variety of distance-uniform (DU) signal sets in Euclidean space. It is shown that four-dimensional signal sets matched to binary tetrahedral, binary octahedral, and binary icosahedral groups lead to better bounds compared to the bounds for signal sets matched to dicyclic groups with the same number of signal points and comparable symmetric PSK signal sets     

Performance analysis of equalized OFDM systems in Rayleigh fading

Channel estimation is usually needed to compensate for the amplitude and phase distortions associated with a received orthogonal frequency-division multiplexing (OFDM) waveform. This paper presents a systematic approach for analyzing the bit-error probability (BEP) of equalized OFDM signals in Rayleigh fading. Closed-form expressions for BEP performance of various signal constellations [phase-shift keying (PSK), differential phase-shift keying (DPSK), quaternary phase-shift keying (QPSK)] are provided for receivers that use a linear pilot-assisted channel estimate. We also derive the optimal linear channel estimates that yield the minimum BEP and show that some previous known results are special cases of our general formulae. The results obtained here can be applied to evaluate the performance of equalized single-carrier narrowband systems as well.     

MFSK-based modulations for hybrid DS/FH-CDMA systems operating inslowly Rayleigh fading channels

This paper presents an analytical evaluation of a direct-sequence/frequency-hopped code-division multiple-access (DS/FH-CDMA) system in a Rayleigh fading environment. The modulations under consideration are noncoherent M-ary-frequency-shift keying (MFSK) and an MFSK-based joint-frequency phase modulation utilizing differential binary phase-shift keying (PSK). Multiple-access interference has been taken into account, and the spectral efficiency for uncoded as well as convolutionally coded systems has been calculated     

Performance degradation of phase-modulated systems due to nonlinear phase noise

The error probability is calculated for phase-modulated systems with nonlinear phase noise. Using the assumption that the phase of amplifier noise and nonlinear phase noise are independent of each other, the error probability and penalty are calculated for both phase-shift keying (PSK) and differential phase-shift keying (DPSK) systems. The mean nonlinear phase shift must be less than about 1.00 and 0.63 rad for a penalty less than 1 dB for PSK and DPSK systems, respectively.     

All-Optical Modulation-Format Convertor Employing Polarization-Rotation-Type Nonlinear Optical Fiber Loop Mirror

An all-optical modulation-format convertor with regenerative function based on fiber nonlinearity is proposed and demonstrated. The convertor was formed utilizing polarization- rotation-type nonlinear optical fiber loop mirror and could operate at both on–off keying (OOK) to OOK and OOK to phase-shift keying (PSK) format conversions only by simply rotating the optical axis of the intra $lambda/2$ waveplate, without excess-loss generation and realignment of the driving conditions of control optical signals in the format exchange. The 40-Gb/s OOK to OOK/PSK format conversions were successfully performed utilizing this new type of the all-optical convertor. The results also revealed that this convertor has a reshaping function to degraded control signals as an inline all-optical regenerator.      

Generalized PSK in space-time coding

A wireless communication system using multiple antennas promises reliable transmission under Rayleigh flat fading assumptions. Design criteria and practical schemes have been presented for both coherent and noncoherent communication channels. In this paper, we generalize one-dimensional (1-D) phase-shift keying (PSK) signals and introduce space-time constellations from generalized PSK (GPSK) signals based on the complex and real orthogonal designs. The resulting space-time constellations reallocate the energy for each transmitting antenna and feature good diversity products; consequently, their performances are better than some of the existing comparable codes. Moreover, since the maximum-likelihood (ML) decoding of our proposed codes can be decomposed to 1-D PSK signal demodulation, the ML decoding of our codes can be implemented in a very efficient way.     

Carrier detection of PSK signals

This paper reports on a theoretical study of the detection of the 2f and 4f carrier components of phase-shift keying (PSK) signals produced by passing signal and noise through a nonlinear device. Unbalanced quadrature PSK (QPSK) signals, i.e., QPSK signals with unequal power in the two channels, are studied. The complete range of channel power ratio is covered, with equal emphasis on the general unbalanced case and the two limiting cases of binary PSK and (balanced) QPSK. Analytic expressions are derived for the detected SNR of carrier harmonics 2f and 4f as a function of SNR, channel power ratio, and normalized input bandwidth. The results apply equally well to PSK data signals and direct-sequence spread-spectrum signals. Measurements confirm every aspect of the theory. The least detectable signal type is balanced QPSK, which is detectable (at 4f) at a threshold SNR ranging from -2 to -13 dB as the detection process gain (chip or data rate/detection bandwidth) is varied from 40 to 80 dB