Coherent and Noncoherent Detection CPFSK

Continuous phase frequency shift keying (CPFSK) is potentially an attractive modulation scheme for use on channels whose performance is limited by thermal noise. In this paper results for the performance available with CPFSK are given for coherent detection and noncoherent detection with arbitrary modulation indices and arbitrary observation intervals. This work serves two purposes. First, it provides interesting, new results for the noncoherent detection of CPFSK which indicate that the performance of such a system can be better than the performance of coherent PSK. Secondly, it provides a complete analysis of the performance of CPFSK at high SNR as well as low SNR and thereby unifies and extends the results previously available.     

Run-Length-Limited Variants of Duobinary and Modified Duobinary

Techniques for varying duobinary and modified duobinary, which are two of the most important partial-response codes, to limit their run lengths without destroying their minimum bandwidth property, are introduced. One of the example codes is the first run-length-limited variant of duobinary ever known, and the other two are already publicized variants of modified duobinary, but are described either in more detail or from a different point of view. Performance figures of the three codes such as power spectrum, eye width, and error probability are experimentally confirmed to be acceptable for all engineering purposes.     

Error Performance Analysis for Narrow-Band Duobinary FM with Discriminator Detection

Of the more band-efficient constant envelope digital modulations, duobinary FM is attractive in terms of its potential error performance, as indicated by the minimum distance of the signal structure. In this paper, the error performance of narrow-band duobinary FM, with discriminator detection in an additive Gaussian noise background, is evaluated for a range of system bandwidthsBTand frequency deviation ratiosh. The effects of intersymbol interference, due to the restricted bandwidth, are taken into account in the analysis. In addition, at the narrower bandwidths,0.5 leq BT < 1.0, the filtered background noise is correlated, and these effects are included. It is shown that with the usual duobinary detector, "clicks," which are a major contributor to errors in conventional digital FM, do not contribute significantly to errors for the low frequency deviation ratios which are commonly used. The error rate theory agrees well with results obtained experimentally. The deviation ratios that give the best error performance for a given system bandwidth are presented. In a narrower bandwidth such asBT = 1/2, where duobinary FM is proposed, duobinary FM with a frequency deviation ratio ofh = 0.7performs better than binary FM.     

多码元差分解调CPFSK算法的改进

连续相位频移键控（CPFSK）信号广泛应用于便携式移动通信系统。在CPFSK的各种解调技术中,多码元差分解调方案表现卓越。但是,该算法存在硬件开销大的缺点。为了解决这一问题,提出了一种更实用的多码元差分解调改进型算法。当采用完全响应4CPFSK信号,在AWGN信道下,BER性能达到10^-3时,提出的改进型算法比原始算法在Eb／N0方面多需要0．9dB,但它的系统复杂度只有原来的1／10。所以,改进型算法更适合于移动通信系统的应用。     

Symbol Error Probabilities for M-ary CPFSK: Coherent and Noncoherent Detection

Continuous-phase frequency shift keying (CPFSK) is discussed and theoretical predictions for symbol error probabilities are derived, where the memory inherent in the phase continuity is used to improve performance. Previously known results concluded that binary CPFSK can outperform coherently detected PSK at high SNR. New results presented here show thatM-ary CPFSK outperforms more tranditionally usedM-ary modulation systems. Specifically, coherently detected quaternary CPFSK with a five-symbol interval decision can outperform coherent QPSK by 3.5 dB, and octal coherent CPFSK with a three- symbol decision can outperform octal orthogonal signaling by 2.6 dB at high SNR. Results for coherently detected and noncoherently detected CPFSK are derived. These performance improvements are estimates derived from symbol error probability upper bounds. Monte Carlo simulation was performed which then verified the results.     

基于连续相位频移键控调制的物理层网络编码检测及性能分析

针对双向中继信道,该文提出一种基于连续相位频移键控(CPFSK)调制的物理层网络编码(PNC)机制,即CPFSK-PNC。与已有的采用BPSK, QPSK等调制方式的物理层网络编码相比,该机制引入CPFSK的技术优势,提高了系统的频谱效率和功率效率。该文对瑞利衰落信道中CPFSK-PNC的物理层网络编码检测进行了研究。首先,利用CPFSK信号的记忆特性,根据最大似然准则设计了中继节点的物理层网络编码检测方案;其次,分析了信号之间最小欧氏距离并给出中继检测的平均误比特率下边界;最后,仿真验证了理论分析结果。     

Realisation of nonlinear CPFSK signals

Nonlinear CPFSK signals are realised with a finite state machine and a constant h CPFSK modulator. Schemes that perform significantly better than those reported in the literature, at the same degree of complexity, are presented.<>     

Coding CPFSK for differential demodulation

A model is developed for finding codes for differentially demodulated continuous phase frequency-shift keying with modulation index h=1/M, where M is the size of the symbol alphabet. The results of codes searches show that there is very little loss in squared Euclidean distance when comparing differential codes with coherent codes     

Calculation of Duobinary Transmission Systems with Optical Waveguides

A calculation and optimization method for optical waveguide transmission systems using the principle of digital duobinary transmission is presented. Then, systems with duobinary reception and systems with raised-cosine reception, which also need an equalizer at the receiving end, are compared with regard to the energy per single signal required for a tolerable bit error probability. Other criteria of comparison, such as susceptibility to jitter, additional duobinary system hardware, and error detection facilities, are considered, too. The results of the calculations show that in an optical waveguide transmission system where the duration of the signal at the optical waveguide output exceeds a defined value, the performance of the duobinary system is better than that of the raisedcosine system when the attainable repeater section lengths are compared.     

Multiple symbol trellis coding of CPFSK

This paper describes a technique related to the design of a trellis encoder, combined with the full response M-ary continuous phase frequency shift keying (CPFSK) with modulation index 1/M. A new representation of CPFSK waveforms in N signaling intervals, is proposed as a function of an (N+1)-D vector. We also decompose the generation of the proposed CPFSK waveform into two stages, an N-consecutive continuous phase encoder (NCPE) and a memoryless modulator (MM). This decomposition makes it possible to design binary convolutional encoders with various code rates, cascaded to the NCPE. Specific optimal outer convolutional encoders of two and three-consecutive full response four-ary CPFSK with modulation index 1/4 are designed following Ungerboeck's (1982) set partitioning approach. These codes achieve asymptotic coding gains up to 4.77 dB for the two consecutive case with code rate 3/4, and asymptotic coding gains up to 5.45 dB for the three-consecutive case with code rate 5/6     

Efficient calculation of multimode CPFSK spectra

The letter shows how previously developed analytic formulas for spectral calculations can be extended to handle the multi-mode CPFSK case. The results are easily programmed, and give fast run times. A numerical example of this method is included.     

Half-Rate Duobinary Transmitter Architecture for Chip-to-Chip Interconnect Applications

For a high speed duobinary transmitter clock frequency defines the transmission limit. A conventional duobinary transmitter needs a clock frequency equal to the data rate. In this work we propose a duobinary transmitter that uses a clock frequency half of the output data rate and hence achieves double the transmission rate for a given clock frequency as compared to a conventional duobinary transmitter. In the proposed transmitter the duobinary precoder is integrated into the last stage of a tree structured serializer to combine two NRZ data streams at half the transmission data rate. Two modes for the precoder have been incorporated into the design. The first mode is applicable for data transmission over copper whereas the second mode is suitable for wavelength division multiplexed optical transmission. A DLL based clock multiplier unit is employed to produce the high frequency clock with 50% duty cycle needed for the precoding operation. It incorporates a clock generation logic with integrated duty cycle control. A charge pump with dynamic current matching and a high resolution PFD are employed to reduce static phase error in locking and hence achieves improved jitter performance. A new delay cell along with automatic mode selection is proposed. To cover a wide range of data rate, the DLL is designed for a wide locking range and maintains almost 50% duty cycle. The design is implemented in 1.8-V, 0.18 μm Digital CMOS technology with an f _T of 27 GHz. Simulations shows that, the duobinary transmitter circuit works up-to 10 Gb/s and consumes 60 mW of power.     

2CPFSK的减少状态格状图

本文在不减少２ＣＰＦＳＫ的自由平方欧氏距离的前提下，提出了２ＣＰＦＳＫ的减少状态格状图，从而减少了维特比译码的复杂度。     

光双二进制技术在城域光网络中的应用

对一种新型光部分响应数字传输技术即光双二进制技术的特点与发展趋势进行了深入研究和介绍。在详细阐述光双二进制系统的实现原理及主要实现方式,并介绍该技术的主要性能优越性以及近来研究成果的基础上,认为由于其与非归零等传统调制方式相比所具有的色散容忍度大、频谱窄、频带利用率高等诸多优点,使其在城域光纤网中的广泛应用正在日益成为可能。     

一种CPFSK信号调制指数估计方法

随着通信技术与通信方式的快速发展,通信信号调制方式与通信系统越来越复杂。复杂通信信号连续相位频移键控(CPFSK)由于其频谱利用率高,大量用于卫星通信等领域。针对复杂信号CPFSK的参数估计问题,提出一种基于李雅普诺夫指数的CPFSK信号调制指数估计方法。通过CPFSK信号李雅普诺夫指数与调制指数的数学关系模型,提取李雅普诺夫指数估计信号调制指数。仿真验证了算法性能,得到CPFSK调制指数估计均方根误差随信噪比的变化曲线。此方法计算复杂度低且实现简单,适用于CPFSK信号与常规频移键控(FSK)信号的调制指数估计。     

Baseband pulse shaping in CPFSK modulation

The performance of M-ary pulse shaped signals is compared with that of CPFSK signals in a narrowband channel at modulation index 1/M. Three symbol by symbol detection techniques are considered for signal detection. It is shown that M-ary pulse shaped signals perform significantly better than M-ary CPFSK signals, and are significantly less sensitive to symbol timing errors.<>     

多进制CPFSK的减少状态格状图

连续相位调制的最佳相干解调的误码性能取决于其最小平方欧氏距离。本文在不减少其最小平方欧氏距离的前提下，提出了多进制ＣＰＦＳＫ的减少状态格状图，从而减少了维持比的译码复杂度。     

Multichannel CPFSK coherent optical communications systems

A detailed theoretical analysis of multichannel coherent CPFSK communications systems is presented. The analysis accounts for the crosstalk between adjacent channels, the intersymbol interference and correlation between noise samples stemming from the limited IF bandwidth the non-Gaussian statistics of the noise at the decision gate, and the impact of the laser phase noise. It is found that the IF bandwidth needed to avoid intersymbol interference is 2.2 bit rates for a modulation index m=1; it is larger for other modulation index values. For m=1, receiver sensitivity is within 1 dB of the shot noise limit, and the electrical domain channel spacing can be as small as 2.05 bit rates with 1-dB sensitivity penalty. The foregoing conclusions are valid for a negligibly narrow linewidth; the degradation due to phase noise is shown to be modest as long as the linewidth does not exceed 1% of the bit rate if m=1. Larger linewidth can be tolerated if the modulation index is larger than unity     

Power spectra of M-ary variable index CPFSK

A generalised closed form expression for the power spectral density (PSD) of M-ary variable index continuous phase FSK (VI CPFSK) has been derived using the Transform technique. Examples are presented for typical cases with input levels 2, 4 and 8. Approximation results are presented for comparison.     

Nonlinear multipulse block coding of CPFSK signals

A nonlinear multipulse block coding technique is proposed to improve CPFSK signaling formats. The coding technique is developed to prevent merging events with lower distances by separating the respective paths in the time domain. Coded schemes are constructed with constant h, 2-h, and trellis coded CPFSK signals. The spectral variations and the performance/bandwidth tradeoffs of the proposed coded signals are found and compared to those without coding. It is concluded from the numerical results that the proposed coding technique can significantly improve the performance/bandwidth tradeoff of many CPFSK signaling formats, particularly, at lower bandwidths