WiMAX的最新动态

由于WiMAX的速度比3G快,基站的覆盖范围比3G大,因此就产生了“WiMAX能否取代3G”的问题。但是实际上,WiMAX与3G在本质上是不同的。WiMAX是一种无线城域网(WMAN)技术,而3G是一种广域城域网(WWAN)技术,两者分别立足于MAN与WAN两种不同领域的技术,两者的基础架构截然不同,WiMAX的着眼点是实现宽带无线化,而3G则更多地是实现无线宽带化。因此。WiMAX与3G将不是替代,而是优势互补,既是竞争,又是互相促进。     

移动WiMAX与3G技术关系的探讨

文章比较了移动WiMAX与3G／E3G的技术特点，探讨了WiMAX与3G／E3G之间的关系，并对移动WiMAX的应用前景进行了分析。     

WiMAX无线宽带技术对传统3G的影响

本文从3G业务定位、WiMAX技术优势和发展趋势等方面阐述了WiMAX无线宽带技术对传统3G的影响,并预测了WiMAX的未来发展趋势。文中认为由于消费需求的影响,使得3G在全球的发展并不是很理想,而特定的WiMAX无线宽带技术优势使其对传统3G构成了一定的威胁。由于WiMAX仍在早期的测试实验阶段,因此在将来,WiMAX与传统3G将形成一个互补共存的运用局面,并在重叠区有一定程度的彼此竞争。     

MiMAX，不甘心只做配角

WiMAX的商用脚步声越来越近，因为WiMAX 不甘心只做配角，其对3G的绝地反击战略已经开 始正式上演。但是要想成为未来移动通信市场的主 角，WiMAX还要经历一段艰辛而长远的路程。 WiMAX作为与3G并驾齐驱的新兴通信技 术，却一直没有受到业界对3G那样的拥戴。与光 环笼罩的3G相比，WiMAX总是被人们“边缘 化”。的确，WiMAX在标准化、商用进程等方面明 显落后于3G，但是WiMAX并不甘心永远做配角， 其对3G实施绝地反击的野心已由最近的“行动” 中表现出来。但WiMAX有这个实力吗？ 最近，WiMAX全球峰会登陆中国，WiMAX全 球论坛主席RonaldResnick亲自上阵呼吁中国支 持；摩托罗拉加入WiMAX阵营；就连近期举行的     

WiMAX与3G是敌还是友

近来,随着WiMAX技术的不断发展和标准的不断成熟,业界对于WiMAX和3G之间的关系讨论的越来越热烈。WiMAX和3G究竟是竞争的关系还是相互补充共同发展的关系呢?本文的作者对于这个问题给出了自己的思考和答案。摩托罗拉(中国)电子有限公司所撰《WiMAX与3G是敌还是友》一文首先明确了WiMAX与3G是可以相互共存的,WiMAX能够成为3G非常有力的补充。然后说明了WiMAX能够给缺乏3G频谱的运营商发展高速数据业务,给固网运营发展移动电信业务,以及给在尚无宽带的农村地区和新兴市场迅速部署通信设施提供了可能。最后提出了WiMAX未来发展的几大关键因素。本文对于我们明确WiMAX和3G的定位与未来发展方向具有一定的参考价值。     

无线宽带技术:从多元竞争到多元融合

WiMAX与3G的竞合 对WiMAX来说,现阶段以及即将到来的2008年是一个非常重要的时期.2007年上半年,WiMAX的全球市场拓展步伐已经开始加速.虽然正式商用的网络数量,特别是基于移动WiMAX的商用网络在现阶段并不多见,但是关注WiMAX并参与其中的运营商数量正在不断增多,很多设备厂商在发展3G的同时涉足WiMAX产业.同时,部分区域3G/3.5G商用的推迟,也对WiMAX产生了正面的推动力量.     

WiMAX不是移动运营商的灵丹妙药

WiMAX误区 目前电信圈内对WiMAX在认识上有几个误区:第一,WiMAX已是3G的有力竞争者;第二,目前移动WiMAX已经全面开始商用;第三,WiMAX的性能将会大大超过3G.     

WiMAX与xDSL、Wi-Fi、3G的比较

文章从技术、应用和市场的角度将WiMAX与其他主流有线和无线宽带接入技术:xDSL、Wi-Fi和3G进行了分析比较.文章指出与xDSL相比,WiMAX理论上可以覆盖更大的范围,提供更大的数据传输速率,具有更强的可扩展性;与Wi-Fi相比,WiMAX频段使用适应面更广、伸缩性更强、QoS和安全性能更优;相对于3G,WiMAX单链路的数据传输速率、频谱效率优于3G,与3G增强技术相当.文章认为WiMAX、xDSL、Wi-Fi和3G通过相互补充、相互促进,可以适应不同的应用市场,提供完整的宽带无线接入服务.     

声音

WiMAX的横空出世打乱了移动通信演进的稳健步调。令移动通信界颇感不安的是WiMAX提供的数据业务能力实际上高于目前3G的增强型技术(如HSDPA、HSUPA、DO和DV等),而且,它还提供移动性!面对WiMAX等宽带无线接入技术的威胁,现有3G的性能、速率和业务能力已经不能满足市场与竞争的要求,而后3G(Beyond3G,简称B3G)与4G又远水救不了近火。业界只好见招出招,将B3G的一系列研究成果提前导入3G系统,形成增强型3G(Enhanced3G,简称E3G)的标准需求。E3G技术在3GPP中的正式名称是Long Term Evolution(LTE)。针对WiMAX“低移动性宽带…     

WiMAX进入电信运营商主流视野

一直以来,因为WiMAX与3G存在商业应用的交集,电信运营商对WiMAX的态度都不明朗。但国内3G牌照迟迟不定,加之WiMAX与3G业务的有效互补得到肯定,国内各大电信运营商均开始积极测试WiMAX网络。联通日前公开宣布,在广东、上海、大连等五地测试WiMAX,年内完成。“联通未来将以3G为主,WiMAX作为补充,”上海联通技术总监刘耀进表示,“WiMAX的特点是带宽足够、移动性比较差,目前主要集中在无线接入方面,逐渐向加强移动性过渡。”据悉,联通未来上马WiMAX主要将部署在行业应用领域,向政府、环保等大客户提供服务。中国四大电信运营商目…     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks