基于相似性传播的天波雷达多路径量测聚类

电离层多层结构特性使得天波雷达(OTHR)与目标之间存在多条信号传播路径,进而可能对单目标产生多路径量测。该文考虑了天波雷达多路径量测聚类问题,其需要同时对多路径量测进行电离层传播路径辨识和聚类。由于天波雷达量测模型假设1个目标通过1种电离层传播路径至多产生1个量测,因此需要考虑多路径聚类约束。该文将相似性传播聚类扩展到多路径约束模型,并提出一种新的多路径相似性传播聚类算法。该算法通过构建多路径量测聚类的概率图模型,将聚类问题转化为概率图模型隐变量的推断问题,采用最大和置信传播算法近似求解聚类变量的最大后验概率。算法优点包括可以自动识别聚类团数目,单次消息传播的时间复杂度为量测个数和传播路径个数乘积的平方。仿真实验分析表明,所提算法较多路径多假设聚类算法具有更好的聚类性能。     

计算机串行通信接口及其应用

串行通信是指计算机主机与外设之间以及主机系统与主机系统之间按位进行传输数据的一种通信方式。串行通信所需的传输线少,成本低,不仅适用于近距离的人-机交换及串行存储设备、实时控制系统,而且可借助现有的电话网等通信通道实现远距离传输,所以串行接口是计算机应用系统常用的接口。在设计通信接口时,必须根据需要选择接口标准,并考虑传输介质、电平转换等问题。     

基于移动存储设备的主机安全保护系统

为解决计算机主机系统存在的安全漏洞,增强全性,开发出一款基于移动存储设备的主机安全保护系统（以下简称系统）。系统针对当前个人主机的安全性问题,通过修改主机MBR引导,以及主机唤醒后的Hook函数的访问控制,提出了一种新式的、操作简单,同时具有拓展性的主机安全保护措施,保证非专业行的普通用户的主机不受威胁。系统具有唯一性和不可否认性,防止伪造验证信息。同时验证设备与方式具有可更改和可拓展性,由移动存储设备进行动态加密,使以后每次解密的密钥都是不一样的,即使丢失移动存储设备,MBR很难被破解。经过测试,系统可以有效的解决主机的安全问题,实现主机安全保护。     

TDI携手AmLogic为A/V设备提供全方位媒体互联解决方案

嵌入式USB互连解决方案供应商TransDimension(简称TDI)公司近日宣布,基于普遍采用的USB标准,AmLogic已将TDI的USB主机控制器应用于多种A/V设备的直接互联。AmLogic将通过包括其A/V处理器在内的客户参考设计方案推荐TDI的USB控制器,以加速产品投放市场及完善全方位设计。Amlogic选择使用TDI的TD242LP和TD1120USB主机、外设和OTG控制器来实现PC与便携式媒体设备以及存储设备与A/V设备之间的通信互联。TDI控制器和AmLogic处理器的结合为消费电子产品制造商提供了完整的媒体互联解决方案。融合AmLogic的A/V处理器和TD…     

一种适用于军用无线自组网的可靠多径路由协议

由于在无线环境、移动模型、硬件平台等方面的差异,民用无线自组网协议无法直接适用于军用网络。为军用无线自组网设计了一种新的可靠多径路由协议。首先,设计了新的可靠性、稳定性路径指标和多路径之间的相关性因子,并提出了选择满足单路径指标且互相关因子最低的L条路径的选路算法。仿真结果表明,该协议比DT-MAODV具有更高的投送成功率和更低的端到端时延。     

基于STM32F103的USB主机接口设计

嵌入式USB主机系统在数据存储和交换领域具有很好的应用前景.为了存储和处理嵌入式系统中的大量数据,一种方法是让嵌入式系统具有USB设备接口,以通讯的方式向上位机不断转储RAM中的数据;另一种方法就是让嵌入式系统具有USB主机接口,使嵌入式系统可以直接读写U盘或SD卡之类的移动存储设备,再通过移动存储设备将数据转储到上位机中,不需要嵌入式系统与上位机之间有直接的通讯连接.使用USB控制芯片CH376设计了一个基于STM32F103的USB主机接口,并应用于嵌入式系统中.     

CH378主机方式USB存储设备写入速度提升方法研究

摘要：CH378接口芯片完成对USB存储设备的读写操作,实现大容量数据的便携存储。系统采用MCU控制CH378接口芯片来完成对USB存储设备的读写操作。并对CH378主机方式USB存储设备的写入速度方案进行比较,从而设计一种新的方案对CH378主机方式USB存储设备写入速度有较大程度的提升,经过测试验证,USB存储设备的写入平均速度达517.9KB/s,对同类开发具有很好的参考意义,可以方便地集成于各种测试系统。     

多路径并行传输中传输路径选择策略

该文首先在实验分析的基础上,发现在互联网端到端传输层多路径并行传输(CMT)中,当端到端关联中路径间的特性参数如丢包率和延迟存在较大差异时,部分路径并行传输的吞吐量优于全部并行传输的吞吐量,从而论证了多路径并行传输情况下传输路径选择的必要性及对传输性能的影响。其次,建立了路径吞吐量与不同丢包率和延迟的拟合关系,并以路径吞吐量为路径权值,提出了一种基于路径权值的传输路径选择策略CMT-PW(Path Weight),给出了该策略的算法实现和相应的伪代码实现。仿真实验表明,CMT-PW策略优于传统CMT策略。     

传输延迟感知的多路径并发差异化路径数据分配算法

针对多路径并发传输模型的整体性能在部分通信路径性能突变时会急剧下降的多种原因进行分析,选取对性能影响最大的因素(传输延迟)进行了优化,提出了一种针对多路径并发传输模型的传输延迟感知的路径数据分配算法。通过结合各条通信路径的实际传输延迟来分配多条通信链路的数据发送量,以及各条路径上发送的数据分组序号,减少路径性能恶化对多路径并发传输模型整体性能带来的影响。分析和实验结果表明,本算法能够相对默认的轮询数据分配算法取得较好的运行性能。     

存储性能瓶颈及优化研究

信息化数据在大规模增长,从而带来了存储设备不断增加,存储运维工作量不断增加的困境,因此存储性能瓶颈的优化成为当务之急。进行存储资源池的建设,评析存储设备及其网络、服务器等设备,从多方面分析提高存储性能,为企业的海量数据存储运维提供新的思路和策略。     

流与路径绑定的并行多路径SCTP的设计与实现

随着通信终端上多个网络接口的实现成为可能,并行多路径传输因其具有较高的传输效率而成为研究的热点。本文设计实现了一种SCTP流与路径绑定的并行多路径传输解决方案,将不同的流映射到合适的路径上进行传输,从而解决多路径接收端数据分组乱序的问题,提高网络传输的吞吐量。     

一种Ad Hoc网络中路由软切换策略的研究

提出了一种新的Ad Hoc网络中对路由的维护方法,即基于局部多路径路由维护的路由软切换技术。在当前路由中某段或某几段链路出现问题时,通过建立局部的多路径路由,分担问题链路中的负载,维护网络保持通信连接不被中断;当路由稳定时,从局部多路径路由中寻找一条满足当前主路由通信需要的子路径,并且将数据传输切换到此子路径上,达到路由抢先维护和软切换的目的。该方法能够缩短路由重建的时间,延长单路径路由的寿命,使用多路径维护,避免了网络拥塞出现造成路由中断,能够很好地提高网络性能。     

面向多路径传输中数据隐私性分析的安全模型

In order to investigate the enhancement of data privacy by distributing data packets via multiple paths, this paper formulates a security model and analyzes the privacy problem in multipath scenarios leveraging information theoretic concept. Based on proposed model, a privacy function related to the path number is discussed. We heuristically recommend the optimal path number and analyze the tradeoff among the performance, resource consumption and privacy. For reducing the information leakage, the data schedule algorithms are also proposed. The analytical model can provide guidelines for the multipath protocol design.     

Blind multipath separation and combining technique for signal recovery

To achieve better mitigation of both cochannel interference (CCI) and intersymbol interference, a new structure using generalized estimation of multipath signals in conjunction with maximal-ratio combining diversity for wireless communications over multipath channels is introduced. In this structure, the signal replicas received from multiple paths are first independently produced by a bank of blind spatial filters and then constructively combined by a diversity combining receiver for final signal estimate. The new scheme can be applied on single antenna array or between multiple antenna subarrays. It will be shown, from both theoretical analysis and numerical experiments, that the new scheme provides both space diversity gains and path diversity gains while suppressing the CCIs.     

A Theoretical Evaluation of Parallel Interference Cancellation in M-Ary Orthogonal Modulated Asynchronous DS-CDMA System Over Multipath Rayleigh Fading Channels

In this paper, we tackle the problem of theoretical evaluation for the multistage parallel interference cancellation (PIC) scheme in a direct-sequence code division multiple access (DS-CDMA) system with orthogonal modulation and long scrambling codes. The studied system operates on the reverse link in a time varying multipath Rayleigh fading channel. By applying the Central Limit Theorem and some other approximations to multiple access interference (MAI) and intersymbol interference (ISI), as well as assuming identically distributed chips from a single interferer, the bit error rate (BER) performance of the PIC scheme at any stage can be recursively computed from the signal-to-noise ratio, number of users, the number of path per user, processing gain of the CDMA system, and the average received power of each path. For completeness, the BER expression is derived for chip synchronous and chip asynchronous systems over both equal and unequal power multipath channels. The proposed analysis is validated by the Monte Carlo simulations and proved to be reasonably accurate, and it gives insight into the performance and capacity one can expect from PIC-based receivers under different situations. For instance, the analytical results can be used to examine the convergence property, multipath diversity gains, and near-far resistance of the PIC scheme.     

多径衰落信道下MC-CDMA系统性能分析

该文提出了一种改进的MC-CDMA方案,该方案取发射的符号周期为切普周期的整数倍,允许各子载波经历多径衰落信道,消除了原方案对切普周期和符号周期的限制,并在接收端可对多径信号进行分离。推导出了在多径衰落信道下改进方案的误码率(BER)表达式,并通过计算机仿真进行了验证。与典型的MC-CDMA方案相比,改进的方案不但又获得了多径分集增益,还使系统的性能得到了显著的改善。     

复杂多径环境下的OFDM定时同步改进算法

现有的定时同步算法在第一根径不是最强径的多径信道条件下,易将定时同步位置定在最强径上,而偏移第一根径,导致严重的ISI.文中在基于PN序列的定时同步算法的基础上提出新的算法,进一步引入"和值"计算.仿真结果验证了新算法的正确性,同时表明新算法也同样适用于第一根径是最强径的情况,因而可以广泛适用于多径信道.     

An Efficient Multipath Detection Scheme for CDMA Systems

In conventional CDMA receivers, the detection of multipath components and RAKE finger management is normally based on the received signal energy per path. These schemes essentially overlook the interference component contaminating the total received power. Consequently, they exhibit poor multipath detection capability especially at low signal-to-interference-plus-noise ratio (SINR). In this paper, we present a new scheme for multipath detection that takes into consideration the interference level in each resolved path individually. Specifically, the proposed scheme is devised to estimate and cancel the interference per path before detection. To account for the hardware limitations of the receiver, we propose a low complexity version of the above scheme which can be easily incorporated into the receiver structure. Our results show that the proposed scheme provides significant improvements in the detection probability of multipath components over the energy-based schemes.     

Multipath routing in mobile ad hoc network with probabilistic splitting of traffic

Multipath routing is a burning issue in mobile ad hoc network due to its various advantages over single path routing. Some of these advantages are load balancing, bandwidth aggregation, and fault tolerance. Multipath routing means multiple paths exist between source and destination pair. Many works discussed in section 2 addressed queuing delays, but none of them suggested queuing delay for multiple path deliveries of data in mobile ad hoc network context. In this paper, we have designed a mathematical model to compute delay and throughput for multipath. Our model follow the network of M/M/1 queues, and we have applied Burke’s theorem to calculate the queuing delay of the packet in mobile network scenario. This model can be used to estimate delay and throughput of an individual path. Further, through the analysis the best path for data delivery out of available multiple paths as well as the multipath path can be used simultaneously for data delivery to the destination. Simulation result shows that splitted traffic multiple paths outperform splitted traffic. Therefore, our model is useful for design and analysis of ad hoc network. The simulation work has been carried out in Qualnet simulator.