100-112 Gbit/s complete ETDM systems based on monolithically integrated transmitter and receiver modules

Traditional intensity modulated two-level electrical time-division multiplexing （ETDM） transmission systems working at 100 -112 Gbit/s were investigated. The complete ETDM systems based on monolithically integrated transmitter and receiver modules were demonstrated with biterror-rate （BER） performance of 10-s at 107 Gbit/s, and near error-free standard forward error correction （FEC） threshold （2 × 10 -3） at 112 Gbit/s. The experiment results showed that directly modulated high-speed ETDM transmission systems with the symbol rates at 100 Gbaud and beyond were promising candidate for cost-effective 100 GbE applications and might be a preform of the next generation of Terabit/s Ethernet.

Lower bound on BER performance for maximal ratio combining with weighting errors

The theoretical lower bounds on mean squared channel estimation errors for typical fading channels are presented by the infinite-length and non-causal Wiener filter and the exact closed-form expressions of the lower bounds for different channel Doppler spectra are derived. Based on the obtained lower bounds on mean squared channel estimation errors, the limits on bit error rate （BER） for maximal ratio combining （MRC） with Gaussian distributed weighting errors on independent and identically distributed （i. i. d） fading channels are presented. Numerical results show that the BER performances of ideal MRC are the lower bounds on the BER performances of non-ideal MRC and deteriorate as the maximum Doppler frequency increases or the SNR of channel estimate decreases.

32×10Gbit密集波分复用系统仿真

分析了DWDM技术及系统的设计原理,在此基础上,给出了基于Optisystem的DWDM光传输链路仿真模型的搭建,对复用及解复用后的光信号进行仿真得出光谱图,对链路传输性能及Q因子、误码率、眼图的等参数进行分析,并验证了波分复用系统的正确性和设计方案的可行性,近而得出相关结论。

2.5 Gbit/s光码分多址通信系统研究

以PTDS仿真实验平台为基础,对传输速率为2.5 Gbit/s的光码分多址通信系统性能进行了研究。仿真研究了传输信道和光功率对光码分多址系统性能的影响,分析了传输距离、光纤色散系数、光纤衰减、入纤光功率等与误码率和Q值的关系。

Multi-Bit Sliding Stack Decoding Algorithm for OVXDM

Overlapped x domain multiplexing(OVXDM) is a promising encoding technique to obtain high spectral efficiency by utilizing inter-symbol interference(ISI) intelligently. However, the computational complexity of maximum likelihood sequence detection(MLSD) increases exponentially with the growth of spectral efficiency in OVXDM, which is unbearable for practical implementations. In this paper, based on a novel path metric associating adjacent symbols, we propose a multi-bit sliding stack decoding(Multi-Bit SSD) algorithm to achieve multiple-bit decoding simultaneously in OVXDM. Theoretical analysis is provided for the algorithm, which indicates the relationship between the performance and parameters including multiplexing waveform, overlapping fold and sliding window size. Simulation results show that the proposed algorithm can achieve better decoding performance and higher spectral efficiency than conventional fast decoding algorithms.

基于4 bit-CRC反馈网络的高速LVDS传输优化设计

针对低压差分信号在恶劣环境中高速度、长距离传输链路中的丢数与误码问题,硬件关键电路设计采用高速LVDS芯片搭建,并增加发送端信号预加重与接收端均衡器处理;逻辑上,应用Verilog HDL构建了一种简单、实用的向前纠错反馈编解码方法,数据收发端以每包数据8 KB采用4bit-CRC生成校验结果,接收端判断校验结果一致与否发送重传与非重传RS-422指令,配合收发端使用乒乓缓存,保证数据可靠高效传输。经验证,系统在长度94 m LVDS专用屏蔽双绞电缆中实现了240 Mbit/s零误码传输。

BER Performance Analysis of Asynchronous NOMA with Arbitrary Phase Offset

An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.

Effects of error feedback on a nonlinear bistable system with stochastic resonance

In this paper, we discuss the effects of error feedback on the output of a nonlinear bistable system with stochastic resonance. The bit error rate is employed to quantify the performance of the system. The theoretical analysis and the numerical simulation are presented. By investigating the performances of the nonlinear systems with different strengths of error feedback, we argue that the presented system may provide guidance for practical nonlinear signal processing.

Temporal Error Concealment Technique for MPEG-4 Video Streams

Concerning inter4v mode employed widely in MPEG-4 video, a new temporal error concealment scheme for MPEG-4 video sequences is proposed, which can selectively interpolate one or four motion vectors （MVs） for the missing macroblock （ MB ） according to the estimated MB coding mode. Performance of the proposed scheme is compared with the existing schemes with multiple testing sequences at different bit error rates. Experimental results show that the proposed algorithm can mask the impairments caused by transmission errors more efficiently than 0 MV and average MV methods by consuming more time for different bit error rates. It has an acceptable image quality close to that obtained by the selective motion vector matching （ SMVM ） algorithm, while taking less than half of cycles of operations. The proposed concealment scheme is suitable for low complexity video real-time implementations.

Enhanced quadrature signaling-based cooperative transmission with full rate and full diversity

Quadrature signaling-based cooperative transmission is an efficient and simple scheme to obtain spatial diversity.However,this scheme causes date rate loss compared with direct transmission.In this work,our focus is on recovering from the data rate loss while simultaneously achieving spatial diversity.Particularly,an enhanced quadrature signaling-based cooperative scheme was designed,which can realize full-rate transmission by using the signal space diversity(SSD)technique.Then,accurate bit error rate(BER)expression for the full-rate scheme was derived over independent and non-identically distributed(INID)Rayleigh fading channels.Specifically,a closed-form BER expression is obtained,which is quite tight over the whole SNR range,and thus allows for rapid and efficient evaluation of system performance under various channel conditions.Moreover,an asymptotic approximation of the BER was derived to show that the full-rate scheme can achieve full diversity.Simulation results verify the tightness of the analysis and show that the full-rate scheme significantly outperforms the traditional quadrature signaling-based scheme by about 2 dB with the same complexity order.

DISPERSION COMPENSATION CFBG IN 100km 10Gbit/s RECIRCULATING SYSTEMS

A 10 Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 10-9. The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4× 167.1km ) in the loop with the power penalty fluctuation below 1.0dB. Thus the group delay ripple should be reduced to allow for the wavelength drift of ±5GHz.At the end of this letter, the principles are given for designing long haul recirculating systems with dispersion compensation CFBG.

ADS-B Reception Error Correction Based on the LSTM Neural-Network Model

Standard automatic dependent surveillance broadcast (ADS-B) reception algorithms offer considerable performance at high signal-to-noise ratios (SNRs). However, the performance of ADS-B algorithms in applications can be problematic at low SNRs and in high interference situations, as detecting and decoding techniques may not perform correctly in such circumstances. In addition, conventional error correction algorithms have limitations in their ability to correct errors in ADS-B messages, as the bit and confidence values may be declared inaccurately in the event of low SNRs and high interference. The principal goal of this paper is to deploy a Long Short-Term Memory (LSTM) recurrent neural network model for error correction in conjunction with a conventional algorithm. The data of various flights are collected and cleaned in an initial stage. The clean data is divided randomly into training and test sets. Next, the LSTM model is trained based on the training dataset, and then the model is evaluated based on the test dataset. The proposed model not only improves the ADS-B In packet error correction rate (PECR), but it also enhances the ADS-B In terms of sensitivity. The performance evaluation results reveal that the proposed scheme is achievable and efficient for the avionics industry. It is worth noting that the proposed algorithm is not dependent on conventional algorithms’ prerequisites.

Integrated coherent beam combining system for orbital-angular-momentum shift-keying-based free-space optical links

Orbital-angular-momentum(OAM)multiplexing technology offers a significant dimension to enlarge communication capacity in free-space optical links.The coherent beam combining(CBC)system can simultaneously realize OAM multiplexing and achieve high-power laser output,providing substantial advantages for long-distance communication.Herein,we present an integrated CBC system for freespace optical links based on OAM multiplexing and demultiplexing technologies for the first time,to the best of our knowledge.A method to achieve flexible OAM multiplexing and efficient demultiplexing based on the CBC system is proposed and demonstrated both theoretically and experimentally.The experimental results exhibit a low bit error rate of 0.47%and a high recognition precision of 98.58%throughout the entire data transmission process.By employing such an ingenious strategy,this work holds promising prospects for enriching ultra-long-distance structured light communication in the future.

采用最小似然bit同步的QPSK系统的性能分析

本文分析了简单的ＱＰＳＫ系统采用最小似然ｂｉｔ同步时，其定时误差对系统抗噪性能产生的影响并给出了系统定时误差的均方差与电路各参数间的关系。

采用最小似然bit同步的2PSK系统的性能分析

本文通过对最小似然bit同步定时误差及其与误码率关系的讨论,分析了采用最小似然bit同步的2pck七系统的性能。

EDFA在565Mbit／s光纤数字通信系统上的实验

本文介绍武汉邮电科学研究院光纤光缆部研制的掺铒光纤放大器（ＥＤＦＡ），及其在国产的５６５Ｍｂｉｔ／ｓ光纤数字通信系统上的实验，中继距离可达１９０ｋｍ，系统误码率＜１０—１２。

Performance analysis and design of MIMO-OFDM system using concatenated forward error correction codes

This work investigates the performance of various forward error correction codes, by which the MIMO-OFDM system is deployed. To ensure fair investigation, the performance of four modulations, namely, binary phase shift keying(BPSK), quadrature phase shift keying(QPSK), quadrature amplitude modulation(QAM)-16 and QAM-64 with four error correction codes(convolutional code(CC), Reed-Solomon code(RSC)+CC, low density parity check(LDPC)+CC, Turbo+CC) is studied under three channel models(additive white Guassian noise(AWGN), Rayleigh, Rician) and three different antenna configurations(2×2, 2×4, 4×4). The bit error rate(BER) and the peak signal to noise ratio(PSNR) are taken as the measures of performance. The binary data and the color image data are transmitted and the graphs are plotted for various modulations with different channels and error correction codes. Analysis on the performance measures confirm that the Turbo + CC code in 4×4 configurations exhibits better performance.

CNN-AE在超奈奎斯特无线光通信端到端系统中的性能

符号间干扰的存在使超奈奎斯特(faster-than-Nyquist, FTN)速率无线光通信系统的性能受到严重影响,针对此问题,提出了一种基于卷积神经网络自编码器的端到端通信系统来消除符号间干扰的影响并完成信号的恢复。针对超奈奎斯特信号非正交的特性,采用交替训练算法分别训练发射机和接收机权重,解决监督训练中模型输入输出数据尺寸不匹配的问题。在此基础上,分析了该系统在Gamma-Gamma大气信道中的误码率(bit error rate, BER)性能。仿真结果证明,与采用最大似然估计的传统系统相比,该系统的误码率性能在各种条件因素影响下都有不同程度的提高。当加速因子在Mazo限内时,该系统可以消除FTN成型和湍流信道带来的复杂混合码间干扰,其误码性能几乎与正交传输系统相等。

基于DVB-S2X协议的低轨卫星通信性能仿真分析

介绍了DVB-S2X标准,重点分析了其中高阶调制技术的基本原理和星座映射,在进行星地链路分析的基础上,构建了DVB-S2X标准低轨卫星通信仿真模型,针对DVB-S2X标准中16APSK、32APSK、64APSK调制信号开展仿真试验,以误码率和丢帧率为指标进行通信性能分析。