我国长途传输网的光纤选型

本文首先介绍了当前国家骨干传输网上应用的几种主要光纤，特别讨论了它们在开通超高速１０Ｇｂｉｔ／ｓ以上速率系统时的优缺点，最后提出我国新建光缆网应尽快全面转向Ｇ．６５５光纤，并对Ｇ．６５５光纤的敷设提出了具体建议。     

城域以太网中的电路仿真业务及其应用

文章概述了基于城域以太网（MEN）的时分复用（TDM）电路仿真业务（CES）的概念，简要介绍了基于MEN的CES的主要业务类型，并着重分析了其中的TDM线路业务的主要结构及其运作方式，描述了电路仿真业务的主要接口类型与功能元件，最后对其进行了应用方案与应用前景的简要分析。     

光纤水听器时分复用系统串扰的理论分析与仿真研究

串扰是困扰光纤水听器阵列时分复用技术应用发展的重要问题之一.对时分复用系统中通道之间存在的串扰从理论上进行了深入分析,并运用仿真方法研究了系统中的串扰与光开关消光比、复用通道数等因素的关系.     

一种提高超宽带无线系统干扰容限的方法

超宽带无线电系统常常因窄带干扰强度超出其干扰容限而无法正常工作,自适应陷波技术可大幅度提升其干扰容限.但在超宽带接收机中,实现高阶陷波非常困难,常规方法复杂度高、稳定性差、难于收敛.本文提出一种时分复用并行高阶自适应陷波方法,能同时快速跟踪并有效滤除一个或多个窄带强干扰,使系统干扰容限大幅度提升,且稳定性好、收敛快、对有用信号损伤小.理论分析与仿真结果验证了其优越性,且具有重要应用价值.     

一种用于TDMoIP映射器的设计与实现

文章讨论了TDMoIP的实现方法;由于采用码速调整和全数字锁相环平滑技术使得2．048Mb／s的输出信号,动态范围宽,电路的性能指标完全可以满足ITU-T的有关标准,同时,电路的规模小、功耗低,可靠性高,易于实现。     

Distributed optical fiber perturbation sensing system based on Mach-Zehnder interferometer

A novel distributed optical fiber vibration-sensing system based on Mach-Zehnder interferometer has been designed and experimentally demonstrated. Firstly, the principle of Mach-Zehnder optical path interferometer technique is clarified. The output of the Mach-Zehnder interferometer is proportional to the phase shift induced by the perturbation. Secondly, the system consists of the laser diode (LD) as the light source, fiber, Mach-Zehnder optical interferometers as the sensing units, a 1×N star fiber-optic coupler, an N×1 fiber-optic coupler, a photodiode (PD) detector, and a computer used in signal processing. The entire monitoring region of this system is divided into several small zones, and each small monitoring zone is independent from each other. All of the small monitoring zones have their own sensing unit, which is defined by Mach-Zehnder optical interferometer. A series of sensing units are connected by the star fiber-optic couplers to form a whole sensing net. Thirdly, signal-processing techniques are subsequently used to calculate the phase shift to estimate whether intruders appear. The sensing system is able to locate the vibration signal simultaneously, includ-ing multiple vibrations at different positions, by employing the time-division multiplexed (TDM) technique. Finally, the operation performance of the proposed system is tested in the experiment lab with the conditions as follows: the number of the sensing units is 3, the length of the sensing fiber is 50 m, and the wavelength of the light diode is 1550nm. Based on these investigations, the fiber surrounding alert system is achieved. We have experimen-tally demonstrated that the sensing system can measure both the frequency and position of the vibration in real time, with a spatial positional resolution better than 50 m in an area of 1 km2.     

A travel demand management strategy: The downtown space reservation system

In this paper, a Travel Demand Management strategy known as the Downtown Space Reservation System (DSRS) is introduced. The purpose of this system is to facilitate the mitigation of traffic congestion in a cordon-based downtown area by requiring people who want to drive into this area to make reservations in advance. An integer programming formulation is provided to obtain the optimal mix of vehicles and trips that are characterized by a series of factors such as vehicle occupancy, departure time, and trip length with an objective of maximizing total system throughput and revenue. Based upon the optimal solution, an “intelligent” module is built using artificial neural networks that enables the transportation authority to make decisions in real time on whether to accept an incoming request. An example is provided that demonstrates that the solution of the “intelligent” module resembles the optimal solution with an acceptable error rate. Finally, implementation issues of the DSRS are addressed.     

Mini-slot TDM WDM optical networks

In recent years, optical transport networks have evolved from interconnected SONET/WDM ring networks to mesh-based optical WDM networks. Time-slot wavelength switching is to aggregate the lower rate traffic at the time-slot level into a wavelength in order to improve bandwidth utilization. With the advancement of fiber-optics technologies, continual increase of fiber bandwidth and number of wavelengths in each fiber, it is possible to divide a wavelength in a fiber into time-slots, and further divide a time-slot into mini-slots so that the fiber bandwidth can be more efficiently utilized. This article proposes a router architecture with an electronic system controller to support optical data transfer at the mini-slot(s) of a time-slot in a wavelength for each hop of a route. The proposed router architecture performs optical circuit switching and does not use any wavelength converter. Each node in the mini-slot TDM WDM optical network consists of the proposed router architecture. Three different network topologies are used to demonstrate the effectiveness and behavior of this type of network in terms of blocking probability and throughput.     

几种光传送网技术的比较

随着业务需求特别是宽带业务的增长,人们对高容量系统,特别是光传送网技术进行了大量的研究。目前研究的内容主要涉及到波分复用光网络,光时分复用技术和光码分复用技术。波分复用技术已经在网络中广泛采用,是目前唯一成熟且付诸实用的超大容量光传输系统;光时分复用的研究近几年取得了较大的进展,是未来极具潜力的技术,但远不如波分复用成熟;光码分复用可大大提高光纤的利用率,降低网络成本,简化网络管理,具有较高的网络     

A subarray-synthesis based 2D DOA estimation method

In some satellite communications, we need to perform Direction Of Arrival （DOA） angle estimation under the restriction that the number of receivers is less than that of the array elements in an array antenna. To solve the conundrum, a method named subarray-synthesis-based Two-Dimensional DOA （2D DOA） angle estimation is proposed. In the method, firstly, the array antenna is divided into a series of subarray antennas based on the total number of receivers; secondly, the subarray antennas＇ output covariance matrices are estimated; thirdly, an equivalent covariance matrix is synthesized based on the subarray output covariance matrices; then 2D DOA estimation is performed. Monte Carlo simulations showed that the estimation method is effective.