微带线间远端串扰的电磁仿真研究

为研究降低远端串扰的方法,利用Ansoft HFSS软件对线间串扰进行电磁仿真研究.研究表明,通过添加防护线、覆盖介质层等措施可以降低远端串扰的影响.在一定频率范围内增加RSR结构中金属贴片的长度和数量,使金属贴片厚度接近微带线厚度等措施,会具有更好的效果;选择具有较高相对介电常数的覆盖介质层材料及增大介质层的厚度也可以降低远端串扰的影响.     

针对线间串扰现象的静态定时分析

超深亚微米工艺下，线间串扰是导致电路故障的主要原因之一。尽管可能导致故障的线间串扰的数量巨大，但真正会引起故障的线间串扰却相对较少。因此，如果能在对电路验证或测试前进行静态定时分析，找出那些导致电路故障的线间串扰，则可以有效提高测试生成效率，并降低测试成本。基于此目的，文章在静态定时分析中引入对线间串扰 扰现象的分析，在线时延模型的基础上使用重叠跳变对故障模型，只需要求出与最长通路的重叠跳变对即可。在对ISCAS89基准电路的实验中，各电路需要测试的串扰数平均减少至10％以下。相对于已发表的实验结果，本文的实验结果具有较高的CPU效率。     

经验模态分解算法在角位移传感器信号去噪中的应用

当多个角位移传感器工作在多个电平时,线路间的串扰会导致内部噪声,影响传感器信号输入和输出。设计了角位移传感器线间串扰信号的多层分解去噪方法。在计算角位移传感器信号线间的串扰电压后,分别计算电容耦合和电感耦合的总串扰电压。利用经验模态分解算法对传感器信号进行逐层分解后,得到一定量的残差项和信号分量（IMF）,并将其相加生成新的信号。重复分解计算产生新的信号,然后计算信号分量（IMF）中包含的串扰信号,并根据硬/软阈值消除串扰噪声。仿真结果表明,所设计的方法可以有效地消除角位移传感器线间串扰信号噪声的影响,使传感器采集的角位移测量电路的电压信号更接近无串扰的电压信号,从而保证角位移传感器信号的有效性。     

V-Mesh:面向三维堆叠芯片的低时延低功耗片上网络结构

针对片上网络直径大、功耗高、可扩展性差以及物理实现复杂的问题,提出了一个低直径、且直径为常数的三维片上网络V-Mesh,并为该网络结构提供了VM路由算法.V-Mesh结构由一层2D Mesh子网和多层行/列互连子网通过三维堆叠技术互连而成,具有功耗低的特点,能支持任意多的节点数,可用于三维堆叠芯片中的节点间互连.相对于一种全互连3D片上网络F-Mesh来说,V-Mesh结构采用行/列互连技术大大减少了其长互连线条数,从而减少了功耗和布线复杂度,可扩展性强.理论分析和实验结果表明,和F-Mesh结构相比,V-Mesh结构的时延与其相当,但能够减少约12.5%的功耗开销.和3DMesh相比,在节点数较多的情况下,其时延能降低23%,吞吐量能提高12%,功耗能降低34%.总的来说,V-Mesh和3D Mesh相比各方面具有明显优势;和F-Mesh的互连性能相当,但其物理实现更为简单,布线量小,可扩展性更好.     

PCB传输线间串扰抑制方法分析

研究数字电子技术设备中,串扰是印刷电路板(PCB)上电磁兼容的重要内容之一.为了抑制PCB传输线间串扰,提高系统信号准确性,消除噪音,通常在传输线间插入一列用金属填充的、顶端用微带连接的接地柱线(简称保护带).由于加有保护带的传输线系统结构复杂,理论分析比较困难,利用网络级联的方法对加有保护带的传输线建模进行分析.计算分析结果表明,加入保护带能有效地抑制线间串扰,保护带参数(接地柱间距、半径)的变化对串扰抑制有明显影响.研究对工程中正确设置保护带以降低串扰提供了必要的参考.     

矿用电气设备电缆电磁干扰建模与仿真分析

分析了互连电缆的电磁干扰机理,建立了多导体互连线串扰耦合数学模型;运用有限元分析软件Ansys提取了矿用四芯电缆互联线的电容矩阵和电感矩阵;应用场路结合的方法对电子设备互连电缆进行电磁干扰预测分析,得到了与理论分析相一致的数值计算结果。     

一种新的基于区域的动态XML编码方案

在区间编码和前缀编码的基础上,提出了一种区间编码的改进的编码方案RSD（region-string-dinary）,采用二进制编码策略,可顺序友好的插入位串;提出了新的位串插入算法,可生成有序位串,且不影响已经存在位串的顺序。描述了R S D中节点间结构关系的判定方法。该二进制编码方案和位串插入算法是有效进行查询处理和避免更新时重新编码的基础。实验表明R S D使得更新时完全可避免重新编码,显示出合理的查询处理性能。     

面向片上网络路由器漏流功耗优化的自适应缓冲管理策略

随着单芯片上集成处理器数量的增加,片上网络逐渐成为多核处理器中非常有前景的互连结构.互连网络成为片上多处理器功耗的重要消耗部件之一.而输入缓冲器是路由器漏流功耗的最大消耗单元,采用门控电源是降低其漏流功耗的有效手段.自适应缓冲管理策略能够根据网络中通信量,自适应地关闭/打开缓冲的一部分,从而降低路由器漏流功耗.而为了减小对网络延迟的影响,该策略中采用的提前唤醒技术能够隐藏缓冲的唤醒延迟.在网络注入率较低情况下,两项缓冲不关闭策略下的网络延迟几乎不受唤醒延迟影响.模拟结果显示,在4×4的二维Mesh中,即使网络注入率为0.7,漏流功耗的节约率依然可以高达46％;网络注入率小于0.4时,两项缓冲不关闭策略下的网络延迟最大仅仅增加了3.8％.     

TD-SCDMA系统中扰码资源的规划研究

TD-SCDMA网络的质量很大程度上取决于网络规划的质量,无线参数的规划做为网规、网优中的一个重要部分,对后期整个网络的服务质量有很大的影响,而扰码的分配是无线参数规划中重要的一个考虑因素,对减少邻区之间的相互干扰起着不可忽视的作用.本文首先对扰码之间的相关性进行了简单的分析,其次研究了扰码分配的基本原则,最后提出了一个实用的扰码选取方法,即通过设计的扰码表来选取小区的扰码,最大可能的避免了扰码之间的相关性,使得邻小区间的干扰得以减少.     

基于隔离带方法的两平行微带线间串扰抑制分析

在实际工程中,由于PCB的物理尺寸逐渐趋向于小型化,系统布线趋向于密集化,设计人员很难对强信号线的干扰按照传统的串扰抑制准则进行设计;在此背景下,文章采用在强信号线两边各加一排顶端用迹线连接的接地孔(简称隔离带)的方法来对其进行屏蔽,以减少微带线间串扰;在模型建立过程中添加了微带线高度及接地平面厚度两个参数,完善了采用隔离带方法来抑制线间串扰的仿真模型,并通过Ansoft公司的HFSS软件验证了此方法是有效的;在隔离带参数设置上,仿真结果表明,通过改变相关隔离带参数S1、g、d、h可进一步抑制线间串扰。     

Selected Crosstalk Avoidance Code for Reliable Network-on-Chip

With the shrink of the technology into nanometer scale, network-on-chip (NOC) has become a reasonable solution for connecting plenty of IP blocks on a single chip. But it suffers from both crosstalk effects and single event upset (SEU), especially crosstalk-induced delay, which may constrain the overall performance of NOC. In this paper, we introduce a reliable NOC design using a code with the capability of both crosstalk avoidance and single error correction. Such a code, named selected crosstalk avoidance code (SCAC) in our previous work, joins crosstalk avoidance code (CAC) and error correction code (ECC) together through codeword selection from an original CAC codeword set. It can handle possible error caused by either crosstalk effects or SEU. When designing a reliable NOC, data are encoded to SCAC codewords and can be transmitted rapidly and reliably across NOC. Experimental results show that the NOC design with SCAC achieves higher performance and is reliable to tolerate single errors. Compared with previous crosstalk avoidance methods, SCAC reduces wire overhead, power dissipation and the total delay. When SCAC is used in NOC, it can save 20% area overhead and reduce 49% power dissipation.     

Accurate and Simplified Prediction of AVF for Delay and Energy Efficient Cache Design

With continuous technology scaling,on-chip structures are becoming more and more susceptible to soft errors.Architectural vulnerability factor (AVF) has been introduced to quantify the architectural vulnerability of on-chip structures to soft errors.Recent studies have found that designing soft error protection techniques with the awareness of AVF is greatly helpful to achieve a tradeoff between performance and reliability for several structures (i.e.,issue queue,reorder buffer).Cache is one of the most susceptible components to soft errors and is commonly protected with error correcting codes (ECC).However,protecting caches closer to the processor (i.e.,L1 data cache (L1D)) using ECC could result in high overhead.Protecting caches without accurate knowledge of the vulnerability characteristics may lead to over-protection.Therefore,designing AVF-aware ECC is attractive for designers to balance among performance,power and reliability for cache,especially at early design stage.In this paper,we improve the methodology of cache AVF computation and develop a new AVF estimation framework,soft error reliability analysis based on SimpleScalar.Then we characterize dynamic vulnerability behavior of L1D and detect the correlations between L1D AVF and various performance metrics.We propose to employ Bayesian additive regression trees to accurately model the variation of L1D AVF and to quantitatively explain the important effects of several key performance metrics on L1D AVF.Then,we employ bump hunting technique to reduce the complexity of L1D AVF prediction and extract some simple selecting rules based on several key performance metrics,thus enabling a simplified and fast estimation of L1D AVF.Based on the simplified and fast estimation of L1D AVF,intervals of high L1D AVF can be identified online,enabling us to develop the AVF-aware ECC technique to reduce the overhead of ECC.Experimental results show that compared with traditional ECC technique which provides complete ECC protection throughout the entire lifetime of a program,AVF-aware ECC technique reduces the L1D access latency by 35% and saves power consumption by 14% for SPEC2K benchmarks averagely.     

网格环境下基于编码机制的数据复制研究

本文提出了基于编码机制的网格数据复制思想,通过对副本数据进行线性分组编码,并将其分散保存到网格存储节点,可形成具有纠删能力的编码子副本组.针对目前热点研究的线性分组编码,探讨基于Cauchy Reed-Solo-mon Code、Tornado Code和Random Linear Code的编码数据复制方案,通过建模手段讨论三者的副本数据访问性能和副本数据可靠性,并与传统的完整数据复制和分块数据复制进行时比分析,证明所提出的编码数据复制有着较优的综合性能.具体实验数据进一步说明,编码副本的编码开销占整个数据复制开销的较小比例,表明编码数据复制是具有可行性的技术方案.     

基于低密度奇偶校验码的数据协调技术

低密度奇偶校验码(LDPC)是一种(n,k)线性分组码。当分组码码长较短时,利用常规的编码方法可以完成编码工作。但随着分组码码长的增加,利用常规LDPC的编码方式编码,计算机的内存难以承担。为了解决以上问题,提出两种有效的编译码方案。首先,该数据协调方案不同于传统校验位译码,利用边信息和原始数据产生的校验子进行联合译码;其次,将校验矩阵以稀疏矩阵的形式存储,利用双向十字循环链表只记录1的位置的方式存储校验矩阵,这样可极大地节省内存空间;最后,通过C语言实现可提高编译码的有效性。实验中选取码长105的分组长度,译码器误码率(BER)收敛于1.0dB,每一分组译码时间仅需4s,译码收敛后速率达到24.85kb/s,时效性较强。     

An ID-based remote mutual authentication with key agreement scheme for mobile devices on elliptic curve cryptosystem

Recently, remote user authentication schemes are implemented on elliptic curve cryptosystem (ECC) to reduce the computation loads for mobile devices. However, most remote user authentication schemes on ECC are based on public-key cryptosystem, in which the public key in the system requires the associated certificate to prove its validity. Thus, the user needs to perform additional computations to verify the certificate in these schemes. In addition, we find these schemes do not provide mutual authentication or a session key agreement between the user and the remote server. Therefore, we propose an ID-based remote mutual authentication with key agreement scheme on ECC in this paper. Based upon the ID-based concept, the proposed scheme does not require public keys for users such that the additional computations for certificates can be reduced. Moreover, the proposed scheme not only provides mutual authentication but also supports a session key agreement between the user and the server. Compared with the related works, the proposed scheme is more efficient and practical for mobile devices.     

Sea-of-leads MEMS I/O interconnects for low-k IC packaging

Technology feasibility of MEMS-type chip I/O interconnects (namely Sea-of-Leads or SoL) is demonstrated. Acting like a spring, a MEMS lead can provide high mechanical compliance to compensate for mismatch of coefficient of thermal expansion (CTE) between a Si chip and a composite substrate. The compliant interconnects can provide low-stress connection between a chip and a PWB substrate, and, therefore, are promising to enable wafer-level packaging of IC chips with mechanically weak low-k interlayer dielectrics (ILD). The compliant interconnection also eliminates the need for an expensive underfilling process, which is one of the key challenges for scaling of conventional controlled collapse chip connection (C4) solder bumps in organic flip-chip packages. For the first time, SoL MEMS interconnects were investigated through the whole procedure of process integration, assembly, as well as reliability assessment. Without underfill, the SoL MEMS interconnects survived more than 500 thermal cycles indicating a promising improvement over a regular C4 solder joint. Failure analysis suggests that the MEMS leads do not fracture while failure occurs close to solder-Cu pad interface due to a nonreliable joining. Full reliability potential of the SoL MEMS interconnects may be demonstrated upon optimization of PWB metallurgy, soldermask design and lead compliance.     

再入飞行器低误码率数字化遥测系统设计

针对再入飞行器遥测领域要求存储系统容量大、误码率低、恶劣环境下可靠回收等特点,以及传统供配电方式存在的地面设备组成多、操作复杂、可靠性低等不足,提出了一种适用于再入飞行器的低误码率数字化遥测系统设计方法。系统采用大容量冗余备份存储设计、基于ECC纠错编码算法的低误码率设计、抗高冲击回收防护设计等关键技术,存储容量提高到32GB,可连续存储9h数据,存储器误码率降低至10-10,实现了高冲击条件下的可靠回收;采用基于1553B总线的数字化供配电技术、在线故障诊断技术等关键技术,简化了地面测试设备及操作,节约研制成本,提高了飞行器智能化和测试性水平。该系统已成功应用于某再入飞行器,通过了地面炮击试验和飞行试验考核,获取到了完整的全程飞行试验数据。     

Robust biometrics-based multi-server authentication with key agreement scheme for smart cards on elliptic curve cryptosystem

Conventional single-server authentication schemes suffer a significant shortcoming. If a remote user wishes to use numerous network services, he/she must register his/her identity and password at these servers. It is extremely tedious for users to register numerous servers. In order to resolve this problem, various multi-server authentication schemes recently have been proposed. However, these schemes are insecure against some cryptographic attacks or inefficiently designed because of high computation costs. Moreover, these schemes do not provide strong key agreement function which can provide perfect forward secrecy. Based on these motivations, this paper proposes a new efficient and secure biometrics-based multi-server authentication with key agreement scheme for smart cards on elliptic curve cryptosystem (ECC) without verification table to minimize the complexity of hash operation among all users and fit multi-server communication environments. By adopting the biometrics technique, the proposed scheme can provide more strong user authentication function. By adopting the ECC technique, the proposed scheme can provide strong key agreement function with the property of perfect forward secrecy to reduce the computation loads for smart cards. As a result, compared with related multi-serve authentication schemes, the proposed scheme has strong security and enhanced computational efficiency. Thus, the proposed scheme is extremely suitable for use in distributed multi-server network environments such as the Internet and in limited computations and communication resource environments to access remote information systems since it provides security, reliability, and efficiency.     

FEC-based AP downlink transmission schemes for multiple flows: Combining the reliability and throughput enhancement of intra- and inter-flow coding

We consider downlink access point (AP) networks and the corresponding reliable transmission schemes. It is well known that one can protect the network traffic against packet erasures by forward-error-correcting-codes (FEC). In addition to ensuring reliable delivery, FECs could substantially reduce the amount of feedback traffic, which is critical when designing high-performance AP protocols.In this work, we generalize the FEC-based schemes, also known as intra-flow coding schemes, for multiple downlink flows. In contrast with the classic approach that performs FEC separately on individual flows, we propose a new protocol MU-FEC, which incorporates the recent idea of inter-flow coding to further enhance the achievable throughput. Specifically, MU-FEC guarantees 100% reliability, is oblivious and robust to the underlying erasure probabilities, has near-optimal throughput higher than any existing inter-flow coding protocols, and can be practically implemented on top of 802.11. The design of MU-FEC consists of three components: batch-based operations, a systematic phase-based network coding decision policy, and smooth integration of inter-flow and intra-flow coding. We analytically show that MU-FEC can achieve much higher throughput than intra- or inter-flow coding alone, and validate its performance gain via extensive simulations. To our knowledge, MU-FEC is the first practical protocol that leverages both intra-flow and inter-flow network coding to solve a real-world problem in single-hop wireless networks.     

An ID-based client authentication with key agreement protocol for mobile client-server environment on ECC with provable security

Recently, lots of remote user authentication schemes are implemented on elliptic curve cryptosystem (ECC) to reduce the computation loads for mobile devices. However, most of those remote user authentication schemes on ECC suffer from different attacks and can not provide provable security. Therefore, we propose an ID-based remote mutual authentication with key agreement scheme on ECC in this paper. The proposed scheme not only provides mutual authentication but also supports a session key agreement between the user and the server. The scheme also provides the known session key security, the perfect forward secrecy, the no key-compromise impersonation, the no unknown key-share and the no key control. Compared with the related works, the proposed scheme is more efficient and practical for mobile devices. We also give a security proof under the random oracle.