用于低轨卫星通信系统的DSSS码捕获技术

研究了用于低轨卫星通信的直接序列扩频系统的码捕获技术.首先,分析了低轨卫星通信中影响码捕获的主要因素,在此基础上,综述了码捕获技术的研究发展过程,针对当前码捕获技术用于LEO卫星通信时存在的两个主要问题,即抗载波频偏能力有限和对码频频偏考虑不足,就三种典型的码捕获技术进行了研究,最后指出了码捕获技术的研究方向.     

新型隧道道路照明系统节能方案

隧道照明目前在交通领域越来越普遍,为了能在隧道中更好地发挥照明器件的效果,使人适应隧道内外环境的变化,达到节能环保的目的,从近年来新兴的节能成果“双功率节能电感镇流器系统”入手,从原理、实际应用的可能性、成本及节能效果等方面进行了阐述,并有大量的数据分析,根据实际实验结果得出了新型隧道照明系统的节能方案。     

嵌入式应用中的USB主设备功能

在嵌入式主设备中应用USB主设备将更容易实现 USB已经成为设备和PC之间通信的标准方式,从通用设备(如闪存设备和鼠标)到专用设备,该标准几乎完全替代了其他的串行通信协议. USB外围设备彼此之间不能相互通信,它们只能与具有控制总线能力的USB主设备通信.直到最近,也只有PC具有主设备能力.但目前,许多微控制器也具有了嵌入式USB主设备的功能,这使得嵌入式应用可以连接更加广泛的USB外围设备.     

Energy spectral efficiency tradeoff in downlink OFDMA network

Spectral efficiency (SE) is an important metric in traditional wireless network design. However, as the development of high‐data rate services and rapidly increase of energy consumption, energy efficiency (EE) has received more and more attention. In this paper, we investigate the EE–SE tradeoff in downlink OFDMA network. Different from previous researches, we try to optimize EE and SE simultaneously. First, the problem is formulated as a multiobjective optimization problem (MOP), and its Pareto optimal set is characterized. Then, we convert the MOP to a single‐objective optimization problem (SOP) by the weighted linear sum method and show that it is neither quasi‐convex nor quasi‐concave. After that, a novel algorithm using particle swarm optimization is proposed to solve the SOP. Simulation results validate that the proposed algorithm can efficiently reduce total transmit power and improve EE, although the cost is sacrificing some SE, which could be used to design an flexible energy efficient network in the future.Copyright © 2014 John Wiley & Sons, Ltd.     

Energy efficiency and spectral efficiency tradeoff in downlink OFDMA systems with imperfect CSI

In this paper, we investigate the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in downlink orthogonal frequency division multiplexing access (OFDMA) systems, whilst considering the channel estimation cost and the corresponding effect of imperfect channel state information (CSI) on SE and EE. The problem is formulated as a multi-objective optimization to determine the optimal pilot transmission power, data transmission power and subcarrier assignment, and then transformed into a single-objective optimization problem, which is a non-convex mixed-integer nonlinear programming (NCMINP) and NP-hard. To address it, we propose an efficient algorithm by adopting alternating optimization and convex optimization methods in lower power region as well as approximate conversion and branch-and-bound methods in high power region. Simulation results analyze and validate the performance of EE-SE tradeoff.     

解决高清音频IC设计难题

视频流和图像绘制技术的进步,极大地提高了高清（HD）运动图像的质量。加上家庭娱乐中心逐渐流行,这些因素已成为追求＂家庭影院＂体验以及便携式电子设备发展的重要推动力。除了高清视频之外,高清音频（HD Audio）也随之引入,     

LCD在无线／便携式设备中的应用

LCD的应用范围正随着其自身技术的不断进步变得日益广泛。电信、互联网设备、测试/测量仪器、手持式数据管理设备、控制板自动显示器、办公设备、笔记本电脑和电子游戏机等诸多门类的产品都是LCD一展身手的舞台。在无线/便携式设备领域(比如蜂窝电话和PDA),LCD仍然显现出比其他显示器技术更胜一筹的设计优势。     

LCD在汽车中的应用

作为可配置的汽车内部显示装置的主要用户界面,LCD需要仔细的挑选以确保其显示准确的信息。[编者按]     

为高速应用选择缆线

在光纤和铜线电缆仍然争夺传输数据权利的时候,你应该选择谁 随着世界上的无线应用越来越多,具有讽刺意味的是,在高速环境中使用电线和电缆变得越来越有必要.Danaher Motion公司(伊利诺伊州伍德戴尔市)的一名名叫CarrollWontrop的高级系统工程师说:"无线方式是竞争对手,但是从习惯上而言,让用户进行转换可能很难".     

线性阵列推动了投影应用的发展

面向投影成像应用的光栅机电系统(Grating Electro-Mechanical System．GEMS)激光投影技术可制作出具有宽色域、高彩色位深度和高分辨率的图像。