自适应传输速率MAC层协议的探讨

随着无线通信技术的发展和器件性能的提高,无线网络有能力支持更高的数据传输速率.随之而来的问题是如何提高网络的性能,即根据无线信道的状况而自适应地改变传输参数.文中讨论了媒体访问控制(MAC)层协议上多跳无线网络自适应传输速率的技术方案.该方案运用自适应调制和编码技术,可以最大限度地利用信道的容量,根据不同终端报告的信道情况提供个性的调制与编码选择;对位置较好的用户提供高速率的数据服务,增加系统的吞吐率;并且由于信道的自适应是通过改变调制和编码的方式,而不是像功率控制那样改变发射功率,因此系统中干扰变化很小.     

Proposal for Efficient Routing Protocol for Wireless Sensor Network in Coal Mine Goaf

The existing uneven clustering algorithm have disadvantages of coal mine with long strip structure. This paper proposed a UCEB-CMF protocol to improve the safety of coal mine monitoring system. The new protocol optimize the selection mechanism of the cluster head, avoid the lower residual energy nodes become the cluster head. Improve the calculation method of non-uniform competition radius and the competition way of the candidate cluster head, so the new protocol can ensure the node which close to the Sink node and has the more energy to priority become the cluster head. Propose a multipath routing algorithm according to the characteristics of the node in the coal mine goaf is die easily, it can ensure the persistence of the data transmission. Simulation results show that the routing protocol effectively balances the energy consumption among cluster heads and achieves an obvious improvement on the network life time.     

Proposal for a novel wiggler

A magnetostatic-field configuration that is independent of the axial (z) coordinate is presented. The motion of an electron in the xz plane in this magnetostatic field is determined. The velocities and the orbit of the electron are identical to those in the ordinary FEL (free electron laser) but with other expressions for the parameters ω₀ and a_ω. An expression for the wavelength of the radiation of the fundamental harmonic (λ_s) is derived. Some numeric examples of λ_s and a_ω are given, and it is concluded that the method presented is promising for obtaining high values of a_ω     

Proposal for Q-Modulated Semiconductor Laser

A novel structure and mechanism for high-speed modulation of semiconductor lasers are proposed and analyzed. The modulator consists of an antiresonant cavity acting as a rear reflector of the laser. The change of the absorption coefficient in the modulator results in a change in the reflectivity of the rear reflector, and consequently the Q-factor, the lasing threshold, and the output power. An implementation structure and numerical results for a Q-modulated distributed feedback laser are presented. The monolithically integrated Q-modulated laser has potential advantages of high speed, low wavelength chirp, high extinction ratio, and high power efficiency     

WCDMA系统传输解决方案

随着我国第3代移动通信系统(3G)组网的时间越来越近,如何搭建合理、高效、经济的基础传输网络也越来越受到各个运营商的重视。在对WCDMA系统的结构和传输接口探讨的基础上,通过对异步传送模式(ATM)、同步数字传输(SDH)、多业务传送平台(MSTP)等多种传输技术的分析和比较,结合目前国内主要通信运营商现有传输网络的组网结构和资源情况,就3G移动通信系统三大标准技术的之一的WCDMA系统提出了传输解决方案。     

Proposal for quantum-dot electroabsorption modulator

Quantum-dot, electroabsorption materials are proposed to obtain low internal loss, large absorption modulation, and negative alpha parameters (blue chirped pulses). These characteristics come from the discrete state absorption associated with three dimensional confinement in quantum dots compared to the band absorption of quantum well, quantum wire, and bulk materials. In addition, type II quantum-dot structures are also proposed to obtain the same optical modulation characteristics with the potential for greater immunity to saturation effects.     

Proposal for novel FEL operation

It is shown that free-electron-laser (FEL) operation in a novel wiggler, proposed in a previous paper by the author (1990), is possible. A single-particle approach is used to derive the small-signal gain equation at the fundamental harmonic in this configuration for sufficiently small a_ω. The small-signal gain curve has the same shape as that of the ordinary linearly polarized FEL, but the expressions for the resonance parameter and for the multiplying coefficient in the small-signal gain equation are different. The maximum value of the small-signal gain is proportional to the cube of the interaction region length in the present case, as in the ordinary linearly polarized FEL, but the maximum value of the small-signal gain is greater than that of the ordinary linearly polarized FEL for large enough surface current density     

Proposal for identity-based key distribution systems

Key distribution systems based on identification information are presented. The systems are analogous to the Diffie-Hellman public key distribution systems in which the former use each user's identification information instead of public files used in the latter. The systems do not require centres to distribute work keys or users to keep directories of key-encrypting keys. Therefore, key management in cryptosystems can be simplified by the identity-based key distribution systems.     

有线电视网络改造的建议

我市县级以上网络已运行十年之久 ,用户普遍反映电缆老化、接触不好 ,意见较大。造成用户收看不好的主要原因 ,是电缆网络系统的可靠性不高所引起 ,为此我们每天要投入大量的人力物力进行维护 ,但事倍功半。许多地方提出改造网络的主要办法 ,即实现光缆传输 ,按每个光接点５００户以下建立网络 ,这样可保证电缆放大器串联级数控制在３～５级范围 ,除提高系统的可靠性外 ,还可以开发多功能运用。但是此方案将要有一笔大的投资 ,就遵义市城区内 ,改造网络要投资１千多万 ;还有一个问题 ,即投资这么多经费 ,开发什么项目 ,何时能收回成本 ?从另…     

Proposal for simplified WDM transmission configuration

A new WDM (wavelength division multiplexing transmission configuration for local communications is proposed. In this configuration, the demultiplexing function is performed using narrow spectral sensitivity optical detectors and a demultiplexer is not required, allowing economical and simple WDM transmission. Dual-wavelength WDM transmission of 0.86 ?m and 0.73 ?m over 2 km on GI fibre is experimentally confirmed, using commercially available LEDs for both optical sources and detectors.     

Methodological Proposal for Multispectral Stereo Matching

Remote sensors have begun to capture digital stereoscopic data. Although still monospectral (usually panchromatic), the capture of multispectral or hyperspectral stereoscopic data is just a matter of time. Digital photogrammetric workstations use area-based stereo-matching techniques based on the Pearson (product-moment) correlation coefficient. This is a technique that is not intended to take advantage of the multispectral data. The authors propose a new method that 1) can handle this multispectral information and 2) can take advantage of the spatial relations between pixel locations. The method is based on multidimensional scaling and Procrustes analysis. Our results indicate that the proposed new technique renders more robust results than classical methodology when noise in the original data is introduced.     

Digital Signature Proposal for Mixed-Signal Circuits

A new Built-In Self-Test structure, based on the information provided by the XY-operation (Lissajous curves) is introduced in this paper. A Digital Signature is obtained which is used to discriminate catastrophic as well as parametric defects. High Fault Coverage is achieved when applying the proposed BIST on an ITC'97 benchmark circuit where 92% of the catastrophic defects and 87.5% of the parametric defects analyzed produced digital signatures clearly distinguishable from the golden signature.     

Proposal for spotbeam pattern for GSM-based satellite personalcommunications

A novel satellite footprint design is presented in order to mitigate the GSM synchronisation problems, caused by the potential wide variety of required timing advances, during the access phase of the signalling procedure. It is applied to LEO and MEO constellations and for different satellite channel parameters. Different approaches are presented and their tradeoff in terms of signalling load is discussed     

Proposal for a polarization-independent integrated optical circulator

A polarization-independent waveguide circulator design is proposed which is well suited for monolithic integration. The circulator consists of multimode interferometers, half-wave plates, and Faraday rotators all in waveguide form. The length of the circulator is 712 /spl mu/m. Simulations show the circulator to have 25 dB of isolation and 1.3 dB of insertion loss at a wavelength of 1.55 /spl mu/m.     

STN液晶部分显示的设计方案

基于640×480点阵STN液晶显示模块,提出了部分显示,即减少扫描行数来降低功耗的新型设计方案:一是关闭未用的行驱动器来减少扫描行数,二是使用时序控制电路来减少扫描行数。该方案适用于普通点阵STN液晶显示器。     

TETRA协议分析仪协议栈处理软件的开发

针对完整的TETRA协议分析仪协议栈逻辑复杂和开发难度大的问题,提出了一种满足实际需求的简化开发方案。通过对TETRA协议分析仪协议栈处理软件的架构、同步过程和用户面/信令面检测过程的分析,给出了协议处理软件的主流程框图,并完成该软件的开发。目前该软件已投入到北京市正通TETRA网络的现场测试中,测试结果证明该软件具有完整、准确的测试能力。     

Proposal for optical switch using nonlinear refraction

We propose that using the phenomenon of refraction of two coaxially copropagating beams at the interface of two nonlinear media, a passive all-optical switch could be constructed for future integrated photonic circuits.     

交换机网管系统设计方案

网管是通信专网可靠、稳定运行的重要支撑系统,通信专网发展越快,网管系统就越重要。介绍了专用于H20-20交换机的网管系统的设计方案,阐述了方案的设计思想、传输方式、系统硬件和系统软件等相关内容。该方案在实际应用中效果良好,得到了用户的认可和好评。     

Proposal for a digital pseudorandom number generator

A digital hardware implementation of a linear congruential sequence generator using shift and add techniques of multiplication is described. The sequence is of long period, low serial correlation and is rectangularly distributed. The method has certain advantages over conventional feedback shift register techniques.     

深度图像的目标潜在区域提取算法

目标检测和识别算法通常使用复杂特征以多尺度滑动窗的方式进行分析,运算效率往往非常低。因此,目标性被引入进行目标潜在区域的快速预判断,减少复杂特征需要分析的窗数,从而达到加速算法效率的目的。针对逐步普及的Kinect深度像机,该文提出了一种基于深度图像的目标性分析算法,以提升深度图像的目标检测识别算法的效率。首先基于深度图像的法向量,提出能够有效描述深度图像边缘信息的特征,然后通过支撑向量机学习目标性的分类器,以得分的形式给出候选区域中存在目标的概率,最后基于人眼的视觉机理对不同尺度的目标进行加权。通过深度图公共数据库的实验对比,该算法给定1000个候选区域时达到94.1%的召回率,保证了准确率的同时大大减少了区域数量,能有效的提升目标检测识别算法的效率。