Multifrequency minimum shift keying

A new modulation scheme that produces a constant envelope continuous phase signal set with a compact power spectrum and power efficiency better than that of MSK is proposed. The scheme can be implemented by quadrature-carrier multiplexing of two frequency/phase modulated signals of the type NFSK/2PSK, both with the same frequency in each transmission interval, and with sinusoidal symbol shapes. The generated signal can be viewed in each transmission interval as an MSK signal at one of the N frequencies and is referred to as multifrequency minimum shift keying (MF MSK). Modulation, demodulation, and synchronization circuits are described, and the spectral properties and power efficiency on the AWGN channel are analyzed. Combining a number of attractive attributes such as constant envelope, excellent spectral properties, high power efficiency, and self-synchronization capability, the proposed modulation format lends itself to a variety of applications, one of them being the digital satellite link     

最小移频键控信号的检测和误码性能分析

首先介绍了MSK信号差分检测原理。其次,分析了存在相关高斯噪声和信道有瑞利衰落时MSK的抗噪声性能。结果表明,在高斯噪声时的差分MSK的误码率与DPSK相同;而当信道存在瑞利衰落时将严重影响系统的抗噪声性能。所得结论能为系统的设计提供重要依据。     

Error-control properties of minimum shift keying

A phase representation of minimum shift keying (MSK), which is a general framework suitable for use with other continuous phase modulation (CPM) schemes, is discussed. The representation is used to show that MSK can be viewed as a coded-modulation scheme with an expanded signal set using Ungerboeck's set partitioning concept (see IEEE Trans. Inf. Theory, vol.IT-28, no.1, p.55-67, 1982). The properties which follow from this view of MSK are explored. The uniqueness of the representation of MSK as a coded-modulation scheme and the structural relationships between different versions of MSK are described     

A differentially coherent PN code acquisition receiver for CDMAsystems

New differentially coherent detectors for acquisition of direct sequence spread-spectrum signals are introduced. These detectors are alternatives to the noncoherent detectors that have been considered almost exclusively in the past. The proposed detectors are suitable for commercial code-division multiple-access (CDMA) systems which operate with a relatively large noise floor and provide a surprisingly large signal-to-noise ratio (SNR) improvement over the noncoherent detectors of approximately 5 dB. Under the random code sequence assumption, an exact analysis of the differentially coherent detection performance for both full period correlation (FPC) and partial period correlation (PPC) is carried out. The detector performance in terms of detection and false alarm probabilities for both partial and full period correlations is investigated, and the results are compared with those of classical noncoherent detection. The mean acquisition time for both single-dwell and multiple-dwell acquisition schemes are compared with their noncoherent counterparts     

Decision feedback detection of minimum shift keying

A new decision feedback (DF) receiver for minimum shift keying (MSK) is derived, which uses the previously detected symbols to estimate the initial phase in the current symbol for optimum coherent detection. Some of theoretical and simulated bit error rate (BER) performance results are presented. The results show that the DF detection provides good bit error performance in the AWGN channel, and is also an efficient detection method for MSK in a fast Rayleigh fading mobile channel     

Generalized minimum shift keying (Corresp.)

A generalized minimum shift keying (GMSK) signal is defined, and its equivalence to a modified offset quadrature shift keying signal is shown. A simple formula for the spectrum of a GMSK signal is presented and the spectrum and out-of-band power are computed for two examples.     

Serial concatenated coding scheme with minimum shift keying

A novel serially concatenated coding scheme for use with minimum shift keying (MSK) is proposed. The novelty is to use a mixture of recursive and non-recursive realisations for the MSK modulator. It is shown that this improves the performance of iterative demodulation and decoding of convolutionally encoded MSK signals with a slight decrease in the decoder complexity     

Heterodyne video transmission with differentially encodedquadrature phase shift keying

Heterodyne transmission experiments of multiple video channels using differentially encoded quadrature phase shift keying (QPSK) are described. Combining the QPSK microwave modulation format with the subcarrier multiplexing technique results in a total of 20 video channels at 50 Mb/s being transmitted on 10 microwave subcarriers. Using a differential encoding approach, this system provides good receiver sensitivity and bandwidth efficiency, while maintaining a simple receiver design. No carrier recovery circuit or phase-locked loop is required for demodulation, which greatly reduces the receiver complexity. It is demonstrated that only a standard delay and multiply demodulator are necessary. With optical heterodyne detection, a receiver sensitivity of -37.5 dBm is achieved for the 20 channel system. The extension of this technique to intensity modulated direct detection subcarrier systems along with migration scenarios for digital video and broadband services is discussed     

Doppler frequency shift estimation for differentially coherent CPM

A communication scheme based on continuous-phase modulated (CPM) signals used in conjunction with trellis-coded modulation (TCM) is considered. To keep the complexity manageable, a detection scheme based on differential detection of CPM signals is used. Methods that estimate the Doppler-induced frequency shift from the receiver signal are studied. Since differential detection transforms a frequency shift into a phase shift, the phase estimation problem is examined first. Three Doppler frequency estimation schemes that are based on open-loop structures and that are designed to achieve different ranges of Doppler frequencies that can be estimated are introduced. These estimators show different degrees of complexity and (at least for high signal-to-noise ratios) significantly different estimation errors. Their performance is compared by using a simulation approach     

A digital signal processing type frequency locked loop for frequency shift keying demodulation

In this paper, we propose a digital signal processing type frequency locked loop (DSP-FLL) using a frequency difference detector (FDD). Since the DSP-FLL is controlled by the frequency, the pole of the voltage controlled oscillator vanishes in the baseband equivalent circuit. Therefore, the transfer function becomes first order and a ringing does not occur. Furthermore, it can be understood from the detection property of the FDD that a cycle slip does not occur and the DSP-FLL can pull in the frequency step input up to half of the sampling frequency.     

Phase-noise-free coherent optical communication system utilizingdifferential polarization shift keying (DPolSK)

An optical communication system utilizing differential polarization modulation, which is free from phase noise, is discussed. The system proved to be immune to essentially all phase jitter. Separate square operations for the x and y channels, followed by multiplication of the two-channel outputs, effectively removed phase jitter. The delay-and-multiply circuit was directly incorporated in the paths of the frequency shifter and the coupler to the local oscillator laser, minimizing the optical power loss     

Direct detection optical communication receiver performance for intensity subcarrier frequency shift keying (Corresp.)

The performance of recently developed doubly stochastic Poisson process filtering and detection procedures, as experimentally measured for a direct detection laser intensity modulated subcarrier frequency shift keying communication format, is reported.     

An optimal algorithm for searching a noiselike signal with the minimum frequency-shift keying

An optimal algorithm for seeking a noiselike signal with the minimum frequency-shift keying is synthesized. The algorithm involves estimation of the signal delay time. The noise immunity of quasi-optimal algorithms is analyzed. The proposed algorithms are recommended for application in correlation receivers of noiselike signals with the minimum frequency-shift keying.     

Noise immunity of a quasi-optimal correlation receiver of noiselike signals with minimum frequency-shift keying

A quasi-optimal algorithm for correlation processing of noiselike signals with minimum frequency-shift keying is proposed and its noise immunity is analyzed. It is shown that the immunity of the quasi-optimal receiver to a structural noise is the same as that of the optimal correlation receiver and, in the case of a fluctuation noise, the loss in the signal-to-noise ratio is ～ 1 dB relative to the optimal algorithm.     

Applications of trellis coding to coherent optical communications employing polarisation shift keying modulation

The application of the concept of trellis coded modulation to coherent optical communications using polarisation shift keying modulation is described and analysed. It leads to a receiver formed by a front end which performs the heterodyne detection and the Stokes parameters extraction cascaded with an electronic Viterbi processor operating the maximum likelihood estimate of the transmitted sequence. Results in terms of error event probability obtained analytically and confirmed by simulation show power gains of the order of 3-4 dB without sacrificing bandwidth.<>     

A digital coherent receiver suitable for land-mobile satellitecommunications

Describes an advanced coherent demodulation technique suitable for land-mobile satellite communications. The proposed technique features a combined narrow/wide band dual open loop (DOL) carrier phase estimator, which effectively enables the coherent receiver to track fast phase fluctuations caused by fading, without degradation in phase slip characteristics. Additionally, an open loop phase estimator has inherent quick recovery performance. Its bit error rate (BER) performance is shown to be superior to that for existing detection schemes, achieving a 10^-2 BER at 6.3 dB E_b/N₀ (0.9 dB greater than the theoretical E_b/N₀ condition for perfect carrier phase tracking) for QPSK over a Rician fading channel with the 10 dB Rician factor and the 1/16 baud rate fading pitch. The paper also describes a quick bit timing recovery scheme, with interpolation, featuring an open loop structure. Further, it presents an experimental digital modem developed through the use of digital signal processors     

Multilevel differential polarization shift keying

We analyze the performance of coherent optical communication systems which employ polarization shift keying (PolSK) modulation, introducing for the first time the requirements for multilevel, differential PolSK. For M-ary signal constellations with M>2, the three-dimensional (3-D) nature of the signal constellations within Stokes space requires the use of double-differential modulation and detection (M-DDPolSK). Coding constraints on the signals place an additional restriction on such systems. We present detailed analysis and simulations for a 6-DDPolSK modulation scheme in which the signal points are located at the vertices of an octahedron in Stokes space     

MDPSK信号的一种盲接收机

随着通信技术和数字信号处理技术的发展,通信接收机应具有越来越强的参数识别能力。该文提出一种适用于任意进制的差分相移键控信号(MDPSK)的盲接收机结构,在未知信号制式的条件下,该接收机可以取信号的最佳定时同步、自动识别信号的调制制式,实现信号的盲接收。     

Generation and transmission performance of 40 Gbit/s polarisation shift keying signal

A novel scheme for generation of a 40 Gbit/s binary polarisation shift keying signal based on a LiNbO/sub 3/ Mach-Zehnder modulator is proposed. The signal is successfully transmitted over 50 km standard singlemode fibre with 0.6 dB penalty.