桌域网环境下的ATM互连性能分析

桌域网是９０年代以来兴起的新技术。文章分析了桌域网中从现有ＰＣ总线结构变迁到基于ＡＴＭ技术互国需要的功能特性和,指出ＡＴＭ不能满足某些互连类型的鼗对现有的两种桌域网ＷＡＮ接口方案文章提出一种新型的接口模型。文章还从操作系统方面分析了适应于桌域网环境的软件特性。     

桌域网及其新技术的研究

桌域网是一种适合于多媒体业务需要的小型ATM网 ,是对传统计算机网络的体系结构的一种补充。本文介绍了设计桌域网的基本策略 ,讨论了它的设计目标和特性 ,给出了桌域网的体系结构、网络接入设备及其性能 ,最后提出研究桌域网的几点建议。     

基于USB2.0的高速图像传输系统设计

针对油气井视频检测高速图像采集传输的要求,设计并完成了一套基于通用串行总线（USB）2.0协议的高速图像采集系统。对数字信号处理器（DSP）的主机接口（HPI）、USB芯片的通用可编程接口（GPIF）和端点以及USB固件程序和PC主机应用程序进行了介绍。该系统使用TI公司的C6437高性能DSP芯片作为系统核心,并经由USB接口芯片与PC主机相连接,实现图像采集系统与PC主机之间的高速数据传输。DSP高速图像采集系统应用于油气勘探领域中,实现了井下视频检测。     

计算机USB接口技术研究

通用串行总线USB是一种新型的计算机通信标准,本文利用USB2.0总线接口高速高带宽的优点,介绍了一种能够实现高速数据传输的USB2.0接口系统的设计,为雷达信号从外部向主机的高速传输创造了条件.     

基于USB2.0的高速图像传输系统设计

针对油气井视频检测高速图像采集传输的要求,设计一种基于通用串行总线USB2.0协议的高速图像采集系统。该系统设计是以TMS320DM6437型DSP为系统核心,并通过USB接口器件与PC主机相连,实现与PC主机的高速数据传输。该高速图像采集系统应用于油气勘探实现井下视频检测。     

USB2.0设备接口芯片从模式设计与实现

为了使USB接口能适应多样化的外围设备,以USB高速设备接口芯片的SoC模型为基础,设计并实现了一种从属结构的数据传输模式,详细分析了从模式传输原理、端点工作机制、固件程序设计、仿真平台设计及仿真结果。以Verilog硬件描述语言设计了仿真平台,包括例化Design Ware库中的USB主机验证IP核作为数据发送接收的主机端,外部数据存储器作为外设数据的中转站,并通过比较主机端的发送和回读数据验证了设计的正确性。结果表明,外部控制器可控制处于从模式的USB设备接口芯片,实现数据在主机与设备之间的交互,此模式下能够有效地提高数据的传输速率,改善数据传输系统的工作效率。     

基于嵌入式Linux蓝牙HCI协议的研究与实现

主机控制器接口是蓝牙系统中软硬件之间的接口。HCI的实现对于在具体硬件基础上自主灵活地构建蓝牙协议栈、开发蓝牙应用起着决定性作用。文章对蓝牙的体系结构、主机控制器接口(HCI)层进行了简要介绍,并分析了蓝牙主机控制器接口的工作原理。针对HCI协议进行了流程分析与接口设计,描述了蓝牙协议的设计架构,并对所设计的协议进行了测试,达到了预期的效果。     

基于USB2.0的高速图像传输系统设计

针对油气井视频检测高速图像采集传输的要求,设计一种基于通用串行总线USB2.0协议的高速图像采集系统.该系统设计是以TMS320DM6437型DSP为系统核心,并通过USB接口器件与PC主机相连,实现与PC主机的高速数据传榆.该高速图像采集系统应用于油气勘探实现井下视频检测.     

DSP6416的主机接口(HPI)与USB接口的连接与设计

本文以基于3G技术的移动自组织网(MANET)的研究为背景,用现在较为流行的高速USB接口与DSP的主机接口HPI相连接,成功地解决了MANET移动终端与主机之间的数据交换问题。本文在介绍了TI公司DSP芯片TMS320C6416和CYPRESS公司的USB接口控制芯片CY7C68013特点以后,介绍了两者连接的一种硬件设计以及USB芯片的固件的编写和调试。     

基于USB接口的数据采集设备

为了实现USB接口的数据采集,有效地提高数据采集设备与主机的通讯速度,介绍了一种基于内置USB接口的新型单片机设计的高速数据采集板。包括该系统的硬件构成和软件组成。系统符合USB1．1协议,是一种比较新颖,系统配置灵活的数据采集设备。     

New concepts and technologies for achieving highly reliable andhigh-capacity multimedia wireless communications systems

The rapid growth of multimedia wireless communications services forces the development of advanced digital wireless systems with high reliability and high speed as well as flexibility for varying traffic conditions. To achieve such advanced wireless systems. New system design concepts different from the conventional ones aiming at increasing system capacity for voice transmission would be required. Since multimedia wireless communications require high quality, high speed, and high flexibility as well as temporary and spatial control of traffic under severe fading environments, the so-called conventional system design concept will be insufficient. New system design concepts and techniques for achieving highly reliable and high-capacity multimedia wireless communications are discussed using both time division multiple access (TDMA) and code division multiple access (CDMA) systems. The demands for high-speed and high-reliability mobile, personal, and multimedia wireless communications services strongly require matching with the trunk network constructed by a broadband optical fiber system or wired system     

移动通信的未来

在3G大规模商用以后,多媒体服务与应用将会得到广泛推广,而3G在速率、服务质量、无缝传输等方面的局限性也将日益显露出来,势必需要带宽更宽的无线系统。故移动通信的下一步必定是走向容量更大、速率更高、功能更强的4G,以在移动环境中支持高清晰度视像和其它宽带多媒体业务与应用。     

Uplink and Downlink Coverage Improvements of 802.11g Signals Using a Distributed Antenna Network

A distributed antenna network (DAN) is demonstrated to improve the coverage of in-building wireless services. A doubling in the number of locations with a high throughput is achieved. A detailed analysis of the performance improvement of a three-antenna DAN over a single-antenna system shows that 10-dB more power would be required from the single antenna to achieve a comparable performance. The effect of the additional delay spread generated by the DAN is also discussed, and the conditions under which it does not degrade performance are investigated.     

基于Au1200的无线车载多媒体终端硬件设计

介绍一种无线车载多媒体终端的硬件设计方案,该终端以Alchemy Au1200多媒体处理器为核心,将无线网络技术与多媒体技术相结合,具有音视频播放、远程监控管理、无线数据高速传输、红外遥控等功能,为车载多媒体设备向无线化、综合化过渡提供一种解决方案。经测试,该无线车载多媒体终端硬件运作良好,结果达到设计要求。     

Construction and performance research on variable-length codes for multirate OCDMA multimedia networks

A new kind of variable-length codes with good correlation properties for the multirate asynchronous optical code divi- sion multiple access （OCDMA） multimedia networks is proposed, called non-repetition interval （NRI） codes. The NRI codes can be constructed by structuring the interval-sets with no repetition, and the code length depends on the number of users and the code weight. According to the structural characteristics of NRI codes, the formula of bit error rate （BER） is derived. Compared with other variable-length codes, the NRI codes have lower BER. A multirate OCDMA multimedia simulation system is designed and built, the longer codes are assigned to the users who need slow speed, while the shorter codes are assigned to the users who need high speed. It can be obtained by analyzing the eye diagram that the user with slower speed has lower BER, and the conclusion is the same as the actual demand in multimedia data transport.     

Perceived Quality Measurement Model Supporting Full Session Mobility in Multimedia Service Delivery

Context-awareness is associated with the concept of machines being able to both recognize and react to the surrounding environment, which has accelerated multimedia computing technology to provide user-oriented intelligent services. The goal of this research focuses on the modeling of video quality measurement in seamless video service delivery process considering the mobility patterns of users. Mobility supporting schemes providing seamless multimedia services are classified into host mobility and user mobility. The former refers to a host-level handoff while the latter indicates a user-level handoff. In host-level handoff, the decisive factors affecting the quality of video contents consumption are the total distance between hosts, the distance to resume streaming while the user is in mobility mode as well as the screen size of the end host. The influential parameters affecting the degree of video quality and seamlessness are evaluated by a subjective quality assessment and then a perceived video quality model was developed, accordingly. In addition, the optimal video delivery switching point to enable user mobility based video service is studied through the quality analysis of host mobility services at varying distances among the hosts. Experimental results show that the proposed quality model has high correlation with assessed quality and is useful to enable an adequate seamless mobility for multimedia service delivery.     

穿墙雷达多维参数人体姿态识别方法

现有的人体姿态识别方案大多数是从单一的角度来考察人体的姿态特征,但是仅采用距离像很难体现人体关节的位置信息,仅提取微多普勒特征有时会覆盖掉径向速度不明显的特征.为此,本文首先利用慢时间-距离像和慢时间-微多普勒谱图构建出人体姿态的三维张量数据集,扩展了人体姿态的特征维度,然后采用改进型瓶颈残差模块构成的神经网络提高了人...     

An evaluation of quality of service characteristics of PACS packet channel

A novel application on the recently emerging wireless Personal Communications Systems (PCS) is the multimedia communication. In this paper, we evaluate multimedia communications capability and quality of service characteristics of one of the PCS standards, Personal Access Communications System's (PACS) packet channel (PPC) using simulation modeling. The performance of PPC's slot aggregation and data-sense multiple access techniques are studied by considering the downlink and uplink in a single cell and combined uplink/downlink in two cells and changing various parameters such as the number of users and certain protocol parameters. Interconnection of PPC with the Internet is discussed next. Frame rates of MPEG-1 coded images transmitted in a PACS cell as IP datagrams are determined. Handover characteristics of PPC downlink are studied by changing different parameters such as the cell size, the speed of the mobile host and time between handovers. The results clearly establish that multimedia communication on PPC is only feasible at lower bandwidths and frame rates and only a few users per cell can be supported. Careful tuning of PPC protocol parameters is required. There is one parameter whose variation gives opposite results on the downlink and uplink.     

基于混合核深度适配网络的HRRP目标识别

为了改善基于卷积神经网络（CNN）的雷达目标识别模型的泛化能力,本文将深度适配网络（DAN）方法引入到高分辨一维距离像（HRRP）目标识别中。为了进一步提高DAN方法的性能,创新性地提出了混合核函数MMD代替传统DAN中的多核MMD,设计了基于混合核函数的MMD损失函数。本文使用服从瑞利分布的海杂波来干扰目标域数据。网络模型中使用一维CNN提取特征,使用混合核函数DAN来减少源域和目标域间特征分布的差异。实验表明,相对常规迁移学习方法和DAN方法, 在海杂波影响下该方法可将目标域数据识别率提高15%左右,显著提高了模型的泛化性能和鲁棒性。