Time Division Multiplexing Fiber Bragg Grating Sensor System Using Composite Codes

A novel multi-point sensing scheme to improve the signal-to-noise ratio(SNR),temperature measurement range of the fiber Bragg grating(FBG)sensors is proposed.The new sensing scheme adopted a composite coding technique based on Simplex codes and Golay codes and time division multiplexing technique to enhance the performance of the sensing system.Simulation results,in good agreement with the theory,confirmed that the maximum SNR enhancement of the sensor system employing composite coding based on 15-bit Simplex codes and 16-bit Golay codes was approximately 6.01 dB in comparison to the conventional single pulse case.

Full color ghost imaging by using both time and code division multiplexing technologies

We propose a new full color ghost imaging scheme using both time and code division multiplexing technologies.In the scheme,the speckle patterns of three colors(red,green and blue)are modulated with different time slots and codes.The light intensity is sampled by one bucket detector.Then based on the modulated time slots and codes,we can effectively and simultaneously extract three detection component signals corresponding to three color components of objects from the sampling signal of the bucket detector.Finally,three component images resulting from the three component detection signals can be synthesized into a full color image.The experimental results verify the feasibility of our scheme under the limit of the number of time slots and codes.Moreover,our scheme reduces the number of bucket detectors and can realize high quality imaging even in a noisy environment.

Novel Optical Analog-To-Digital Converter Based on Optical Time Division Multiplexing

A novel optical analog-to-digital converter based on optical time division multiplexing(OTDM) is described which uses electrooptic sampling and time-demultiplexing together with multiple electronic analog-to-digital converter(ADC). Compared with the previous scheme, the time-division multiplexer and the time-division demultiplexer are applied in the optical analog-to-digital converter(OADC) at the same time, the design of the OADC is simplified and the performance of the OADC based on time-division demultiplexer is improved. A core optical part of the system is demonstrated with a sample rate of 10 Gs/s. The signals in three channels are demultiplexed from the optical pulses.The result proves our scheme is feasible.

Light slowing and all-optical time division multiplexing of hybrid four-wave mixing signal in nitrogen-vacancy center

We report the experimental results of hybrid four-wave mixing and fluorescence signals from nitrogen-vacancy(NV)centers in diamond. The fluorescence signals are slowed owing to dark state. The observed delay time of light slowing due to interconversion between NV^- and NV^0 is about 6.4 μs. The relative intensities of read-out signals change with the wavelength and power of writing pulse. Based on light slowing, we present the model of all-optical time division multiplexing. The intensity ratio in different demultiplexed channels is modulated by the wavelength and power of control field. It has potential applications in quantum communication and all-optical network.

A passive optical network based on optical code division multiplexing and time division multiple access technology

A passive optical network （PON） scheme based on optical code division multiplexing （OCDM） for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM technology to guarantee the security, while the upstream traffics pass through the same optical fiber by the common time division multiple access （TDMA） technology to decrease the cost. This schemes are denoted as OCDM/TDMA-PON, which can be applied to an optical access network （OAN） with full services on demand, such as Internet protocol, video on demand, tele-presence and high quality audio. The proposed OCDM/TDMA-PON scheme combines advantages of PON, TDMA, and OCDM technology. Simulation results indicate that the designed scheme improves the OAN performance, and enhances flexibility and scalability of the system.

Design of Simulation for Time-Division Multiplexing Digital Optimal Frequency Band Transmission System

This paper designs a simulation experiment model of the overall structure of time-division multiplexing digital optimal frequency band transmission system based on MATLAB simulation platform. The parameters of each module in the simulation model are set. The working process and performance of the time-division multiplexing digital optimal band transmission system are simulated. The simulation results show that the digital optimal band transmission system achieves the best transmission receiving conditions and performance, and the designed time-division multiplexing optimal digital band transmission simulation system achieves its functions. The research in this paper will help to improve the level of digital communication technology and to understand the structure of time-division multiplexing digital optimal band transmission system.

Implementation of Synchronization Technology in Orthogonal Frequency Division Multiplex System Based on Field Programming Gate Array

In this paper,analyzed is the symbol synchronization algorithm in orthogonal frequency division multiplex(OFDM)system,and accomplished are the hardware circuit design of coarse and elaborate synchronization algorithms.Based on the analysis of coarse and elaborate synchronization algorithms,multiplexed are,the module accumulator,division and output judgement,which can evidently save the hardware resource cost.The analysis of circuit sequence and wave form simulation of the design scheme shows that the proposed method efficiently reduce system resources and power consumption.

Minimizing Traffic Blocking and Inter-Crosstalk in Spatial Division Multiplexing over Elastic Optical Networking

As a promising solution, virtualization is vigorously developed to eliminate the ossification of traditional Internet infrastructure and enhance the flexibility in sharing the substrate network (SN) resources including computing, storage, bandwidth, etc. With network virtualization, cloud service providers can utilize the shared substrate resources to provision virtual networks (VNs) and facilitate a wide and diverse range of applications. As more and more internet applications migrate to the cloud, the resource efficiency and the survivability of VNs, such as single link failure or large-scale disaster survivability, have become crucial issues. Elastic optical networks have emerged in recent years as a strategy for dealing with the divergence of network application bandwidth needs. The network capacity has been constrained due to the usage of only two multiplexing dimensions. As transmission rates rise, so does the demand for network failure protection. Due to their end-to-end solutions, those safe-guarding paths are of particular importance among the protection methods. Due to their end-to-end solutions, those safeguarding paths are of particular importance among the protection methods. This paper presents approaches that provide a failure-independent route-protecting p-cycle for path protection in space-division multiplexed elastic optical networks. This letter looks at two SDM network challenges and presents a heuristic technique (k-shortest path) for each. In the first approach, we study a virtual network embedding (SVNE) problem and propose an algorithm for EONs, which can combat against single-link failures. We evaluate the proposed POPETA algorithm and compare its performance with some counterpart algorithms. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance in terms of spectrum utilization and blocking ratio, even if with a higher backup redundancy ratio.

时间反转OFDM系统中增强安全性能的功率分配与人工噪声设计

时间反转技术特有的时空聚焦特性使其具有抗窃听能力.本文对提高时间反转正交频分复用系统安全性能的优化方案进行研究.首先,通过应用时间反转预滤波的时空聚焦特性来提高合法接收端相对于窃听端的信号强度;然后,以最大化保密速率为目标对子载波的功率分配进行优化.为进一步提升系统保密传输能力,利用循环前缀提供的自由度实现零空间人工噪声,在对窃听端形成有效干扰的同时,不对合法接收端造成影响.通过对子载波功率分配和人工噪声协方差阵进行联合优化,最大化系统的保密传输速率.仿真结果表明,所提优化方案能显著提高系统的保密速率.

基于稀疏贝叶斯学习的GFDM系统联合迭代信道估计与符号检测

针对当前广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统时变信道估计精度低的问题,提出基于稀疏贝叶斯学习的GFDM系统联合信道估计与符号检测算法.具体地,采用无干扰导频插入的GFDM多重响应信号模型,在稀疏贝叶斯学习框架下,结合期望最大化算法(Expectation-Maximization,EM)和卡尔曼滤波与平滑算法实现块时变信道的最大似然估计;基于信道状态信息的估计值进行GFDM符号检测,并通过信道估计与符号检测的迭代处理逐步提高信道估计与符号检测的精度.仿真结果表明,所提算法能够获得接近完美信道状态信息条件下的误码率性能,且具有收敛速度快、对多普勒频移鲁棒性高等优点.

重叠阵元时分复用MIMO雷达多目标参数估计方法研究

针对多普勒-角度耦合和速度模糊问题,该文提出一种基于重叠阵元MIMO阵列的多目标参数估计方法。该方法基于虚拟孔径原理,在传统MIMO天线阵列中引入重叠阵元,构建重叠阵元MIMO天线阵列。通过在角度快速傅里叶变换(FFT)算法中引入循环迭代的方法估计阵列位置参数,利用重叠阵元回波信号的相位差值进行频率估计。同时,引入频谱搬移方法对速度区间进行转换,实现多目标的距离和速度估计。通过蒙特卡罗仿真实验,信噪比15 dB的条件下,解模糊正确率为100%,速度误差为0.1 m/s,角度误差为0.1°。基于城市交通场景采集的车辆数据集进行测试,测试结果表明,该方法能够实现对车辆目标的速度和角度精确估计,可满足交通雷达对车辆信息监测的实时性和准确性需求。

注意力去噪与复数LSTM的时变信道预测算法

随着无线通信技术的发展,高速场景下通信技术的研究也越来越广泛,其中获取到准确的信道状态信息对提升无线通信系统的性能具有重要的意义。针对正交频分复用系统在高速场景下,现有信道预测算法未考虑噪声影响及预测精度低的问题,提出了一种注意力去噪与复数卷积LSTM的时变信道预测算法。首先,设计了一种通道注意力信道去噪网络对信道状态信息进行去噪处理,降低了噪声对信道状态信息的影响。然后,提出了基于复数卷积层和长短期记忆网络的信道预测模型,对去噪后历史时刻的信道状态信息进行特征提取,并且对未来时刻的信道状态信息进行预测;改进后的LSTM预测模型增强了对信道时序特征的提取能力,提高了信道预测的精度。最后,结合Adam优化器对未来时刻信道状态信息进行预测输出。仿真结果表明:与对比算法相比,所提基于注意力去噪与复数卷积LSTM的时变信道预测算法对信道状态信息的预测精度更高,能够适用于高速移动场景下的时变信道预测。

一种面向低成本轻量级雷达的单比特复用阵列信号收发框架

面向低成本轻量级雷达的应用需求,该文提出了一种联合单比特采样量化和时分复用接收机的雷达信号收发框架。首先,通过介绍该框架的工作原理,阐述其在节省接收机数量方面的优势。从雷达资源配置的角度,分析了单比特采样量化在该框架中的重要性,并提出了该框架可利用时间换空间,获得比经典线性调频连续波雷达更好的探测性能。接着,推导了雷达测距、测速和测角公式,以及目标参数估计的克拉美罗界。在此基础上,验证了该框架的性能优势,同时也给出了其稳定工作的信噪比条件。最后,利用一种基于单比特二维多重信号分类的速度维配对算法,验证了该框架获取目标原理的正确性,以及性能分析的可靠性。

面向软件定义互连系统的多协议交换电路

为满足软件定义互连系统中异构协议融合互连的需求,提出一种两级多协议交换电路,该电路通过融合共享缓存与Crossbar这2种交换架构,实现对多种异构协议的报文转发需求的兼顾。同时,提出一种基于时隙的多级仲裁调度方法,实现调度过程中时间与空间的解耦。仿真结果表明,所设计的交换电路能够弹性适应绑定模式变化引起的交换规模及端口缓存、端口带宽需求变化,缓存资源利用率相较传统组合输入输出排队(CIOQ)架构最高提高87.5%,转发时延低至数十纳秒,不仅适用于RapidIO、光纤通道(FC)、Ethernet、外设部件互连快速总线(PCIe)单一协议交换,而且适用于多种协议组合的混合协议交换。

基于光开关阵列的灵活TWDM-PON系统研究

为了满足接入网日益增长的业务流量需求,解决当前因架构固定、资源维度有限而导致的不同无源光网络之间波长无法灵活分配的的问题,提出了一种将发射固定波长的激光器与光开关阵列组合的时分波分混合复用无源光网络结构。在这种新的系统结构中,下行波长资源被集中化处理,采用在局端配置光开关阵列的方法实现波长在不同网络之间的灵活调度,降低系统总体成本的同时能够用来解决负载平衡、流量“潮汐效应”、网络资源利用率低下等问题。通过理论分析和仿真实验验证了系统的可行性,得出该结构与传统无源光网络的兼容性、波长资源的共享性、系统低成本以及节能的特点。结果表明,在没有色散补偿的情况下,信号可以覆盖30 km的传输距离,同时服务512个用户。该研究可以为典型应用场景下的无源光网络部署提供参考。

基于分时复用SAR ADC的Zoom ADC

为了在增加有限硬件开销的基础上实现更高的信号噪声抑制比、提高面积利用效率,提出一种基于分时复用SAR ADC的动态zoom ADC。同时提出一种提取粗量化模拟残差并前馈的无源实现方案,不需要有源求和运放的设计,避免了普通无源求和信号的衰减,减小了粗量化部分量化噪声泄露引起的“毛刺”。整体电路分为粗量化和细量化两部分进行设计,粗量化由3位异步SAR ADC实现,细量化由二阶3位量化的sigma-delta调制器实现。基于0.18μm CMOS工艺、3.3V供电电压,在1MHz采样频率下、1kHz带宽内,消耗76μA电流,得到信噪失真比和FOM的具体值,验证了设计的可行性。

时分复用双光子成像系统高速数据处理研究

为满足高频脉冲时分复用的双独立扫描探测双光子显微成像系统中信号解多路复用、行场同步、像素值重建的需求,对高速数据的采集处理进行了研究;基于LabVIEW FPGA,结合有限状态机、FIFO缓存和并行流水线等技术,设计了一种多功能采集处理系统,通过精确的时序控制,成功实现了高速数据的无损解复用和后续成像数据处理,并能够对共振振镜非线性运动导致的图像畸变进行校正;经过调试仿真和实验测试表明,在系统单通道采样率800 MSPS、200 MHz FPGA处理时钟下,能够对160 MHz时间交错激光脉冲产生的来自不同位置的相应荧光信号进行复杂处理;经实际应用表明,系统满足实时成像的需求,为相关领域的研究者提供了有益的参考。

基于压缩感知的可见光通信定位一体化系统性能分析

为了降低到达时间(time of arrival, TOA)算法的接收信号采样率需求,基于正交频分复用(orthogonal frequency division multiplexing, OFDM)系统中信号具有频谱稀疏性的特点,提出了基于压缩感知算法的可见光通信定位一体化系统。仿真结果表明,采用压缩感知算法后,通信系统仅需原始采样率为100 MHz时数据量的60%即可使误码率降至10-3以下,定位系统仅需原始采样率为800 MHz时数据量的2.1%即可准确估计收发端距离,远低于采样定理所需数据量,证明了所提算法的优越性。此外,在引入噪声后,通过提高压缩感知算法的测量数据比例,一体化系统仍能在奈奎斯特采样率以下保持良好的通信与定位性能。

基于LoRa的多传感器低功耗数据采集方法

针对LoRa多传感器低功耗采集中同信道传感节点无效唤醒的问题,提出一种基于空中唤醒策略与信道切换机制相结合的低功耗采集方法。通过将LoRa通信链路划分为多个通信信道,不同信道分时切换复用,实现多传感节点的分组通信,避免从传感节点的无效唤醒,在有限信道容量下最大限度地降低从节点的通信功耗;并制定了LoRa局域网传感器通信指令协议,实现了多传感器的低功耗主动轮询采集、定点调试与预警上报。实验结果证明了所提方法的有效性。

基于图控分离和2次分类的无人机信号识别方法

无人机(unmanned aerial vehicle, UAV)行业的快速发展给重要场所的低空空域带来安全隐患.为了对无人机实施有效管制,研制一套能够识别无人机信号的无线电侦测系统有重要意义.针对相似无人机之间识别困难的问题,提出了一种基于图控分离和2次分类的无人机信号识别方法.该方法基于无人机图像传输信号(image transmission signal, ITS)的循环特性提取其时域参数,采用分类决策树对无人机进行初步分类识别;再通过分离无人机的图像传输信号与飞行控制信号(flight control signal, FCS)的方式分别提取其时频特征参数;最后进行了2次分类识别.实验结果表明,对于6种常见无人机的通信信号,在信噪比(signal-to-noise ratio, SNR)为0 d B时平均识别准确率可达97.4%,说明该方法可以精确识别无人机.