MIMO-OFDM系统无线衰落信道容量分析

推导了MIMO-OFDM系统在衰落信道下的各态历经容量、最优发送策略、使用等功率分配时的容量上界以及相对于单天线OFDM系统的容量增益。结果表明：天线数和平均接收信噪比是决定MIMO-OFDM系统信道容量的关键因素。天线数越多或者接收信噪比越大,信道的容量越大,信道容量几乎不受多径时延扩展的影响。慢衰落信道下的最大信道容量可以使用空-频两维注水算法得到,当接收信噪比足够大时,最大信道容量也可以用平均分配发送功率的方法逼近。     

多天线无线数据通信系统中多用户分集的研究

研究当接收天线不少于发送天线时多输入多输出(MIMO)系统的多用户分集能力。首先从理论上分析了发送天线个数等于1和2时最大似然接收和迫零接收系统的平均吞吐量和调度增益,以及仿真分析了发送天线个数大于2时系统性能。理论分析和仿真表明：在多用户的MIMO系统中,接收的平均信噪比、用户个数、收发天线个数、接收机的结构等对于多用户分集有很大的影响。当发送天线个数为1时,接收天线较少(1,2,3)和平均信噪比为．10dB时调度增益很大,但调度增益随着天线个数和发送功率增大急剧下降。和最大似然接收相比,迫零接收具有更大的多用户分集增益,因此迫零接收机的吞吐量可以很容易超过最大似然接收机。     

三维目标电磁散射的自适应积分方法

应用自适应积分方法并结合邻近组预条件求解三维导电目标的电磁散射.通过建立辅助基函数将三角形分域基函数映射到矩形网格中,并将格林函数离散变换为具有Toeplitz特性的矩阵.用快速傅立叶变换加速迭代求解中的矩阵和矢量相乘,该方法极大的减少了内存需求和CPU时间,其存储量和运算复杂度分别为低于O(N1.5)和O(N1.5logN)量级.应用邻近组预条件技术进一步降低了迭代求解所需的迭代次数.数值结果表明了该方法的准确性和高效性.     

深圳地面数字电视单频网建设出现的一些问题讨论

数字电视单频网(SFN)就是由多个发射台发射组成的数字电视覆盖网络,所有发射台采用同一个频率在同一时间发送同一个节目。在都市内,电视台发射的开路信号,容易受到众多高层建筑物遮挡和多径干扰的影响,使接收效果恶化。     

Emergint:一种支持多节点并发动态增删的P2P路由算法

针对P2P网络动态构建问题,提出了一种能够支持多节点并发动态加入和退出的P2P路由算法.该算法具有如下特点:(1)自治性:节点的增删不需要统一控制;(2)动态性:节点的增删不影响其他节点路由过程的正确性;(3)并发性:多节点可以同时加入和退出系统,彼此不干扰.该算法的路由延迟为logN.模拟测试结果表明:该算法的平均RDP为1.5,增删节点的代价为O(logN).     

亚微米CMOS结构光学交叉互连电路芯片的设计

同单路光接收／发送电路系统相比,采用单片集成的多路交叉互连接收／发送系统可实现大容量信息交换和高度复杂的信息处理。给出了与１０×１０阵列多量子阱（ＭＱＷ）器件芯片倒扣连接的接收／发送交叉互连电路的设计,芯片电路采用０．３５／０．５μｍ设计规则、三层金属布线ＣＭＯＳ结构,在２ｍｍ×２ｍｍ芯片上,可完成１６路接收／发送及１６×１６信号交叉互连的功能。     

STBC块传输系统中的一种新型分集合并算法

该文在二发一收的空时分组码(STBC)单载波块传输系统中,提出一种空时和多径分集合并接收算法。通过基于STBC的单载波频域均衡(STBC-SC-FDE)算法得到对发送信号的估计,以此和信道状态信息(CSI)分离接收信号中的各多径分量,对各多径分量分别采用STBC合并,最后再将各多径分量的合并输出结果按照最大比(MRC)的方式进行合并,从而实现空时二维RAKE接收。该算法在较低的计算复杂度情况下,可以同时获得发射分集和多径分集,Monte Carlo仿真验证了该算法的性能。     

彩信端到端成功率优化策略

1 点对点业务发送环节分析 端到端彩信的发送、接收过程指所有类型的发送终端(SP、电脑、手机)到手机的彩信发送、接收过程,以下简称端对端业务.手机报为移动运营商近几年推出的一种SP到手机的彩信业务,在福州移动,其占所有端到端业务的70%以上.点到点彩信发送、接收过程仅指手机到手机的彩信发送、接收过程,以下简称点对点业务.目前在福州移动其只占端对端业务的14%左右.     

三维电大目标散射求解的多层快速多极子方法

为进一步提高对电大尺寸目标散射求解的能力,详细研究了多层快速多极子方法.重点设计了用于多层快速多极子方法的各种优化方法包括Morton编号、转移因子修正内插技术与外向波重复存储策略.对于未知量数目为N的三维电磁散射,数值实验显示多层快速多极子方法具有O(NlogN)量级的计算量、O(N)量级的存储量,特别适合求解三维电大尺寸目标的电磁散射.利用该方法在单机(内存1Gb)上成功计算了未知量为25万的电大尺寸目标散射.     

自适应波束形成的SARLS算法

提出了一种改进的递推最小二乘(RLS)算法——子阵异步RLS算法(SARLS)用于自适应波束形成,改进后的算法,在总权矢量的维数为N、子权矢量维数较小时,运算量由O(N2)降到了O(N),并通过实例仿真详细地验证了算法的实用性:该算法在保持对期望信号良好接收的同时,能够很好地抑制到达方向与期望信号不同的干扰信号。     

一种具有O信息复杂度的高速crossbar调度算法

本文提出一种可扩展性强的高速crossbar调度算法——iRGRR(iterative request-grant-based round-robin),它通过简化处理流程和减小调度开销,克服了传统算法(例如iSLIP^[1]、PIM^[2])可扩展性差的缺陷.iRGRR将控制信息复杂度从O(N)级大大减小到O(logN)级,具有良好的可扩展性,可应用于太比特交换机/路由器中.仿真结果表明,在各种不同的均匀和非均匀业务流下,iRGRR能够获得与iSLIP几乎相同的性能.另外,iRGRR比iSLIP具有更好的公平性以及更加易于用硬件实现.     

A new design for wide-sense nonblocking multicast switching networks

In this paper, we propose a new design for a wide-sense nonblocking multicast switching network, which has many comparable properties to a strictly nonblocking Clos permutation network. For a newly designed four-stage N/spl times/N multicast network, its hardware cost, in terms of the number of crosspoints, is about 2(3+2/spl radic/2)N/sup 3/2/=11.66N/sup 3/2/, which is only a small constant factor higher than that of a three-stage nonblocking permutation network, and is lower than the O(N/sup 3/2/(logN/loglogN)) hardware cost of the well-known three-stage wide-sense nonblocking multicast network. In addition, the proposed four-stage nonblocking multicast network has a very simple routing algorithm with sublinear time complexity, and does not require multicast capability for the switch modules in the input stage.     

一种可扩展的常数度P2P系统

DBR图是一种节点出度和入度均为2的常数度的图.通过将DBR图应用到动态网络,设计并实现了一种可扩展的常数度的P2P系统.对于节点规模为N的Tangram系统,路由表大小为O(1),平均路由步数是O(logN).通过模拟网络的实验表明,Tangram系统具有高效的查询性能,平均路由步数显著低于其他常数度P2P系统,在不同的节点在线率情况下性能稳定.     

Fast solution of mixed-potential time-domain integral equations for half-space environments

A fast Fourier transform-accelerated integral-equation based algorithm to efficiently analyze transient scattering from planar perfect electrically conducting objects residing above or inside a potentially lossy dielectric half-space is presented. The algorithm requires O(N/sub t/N/sub s/(logN/sub s/+log/sup 2/N/sub t/)) CPU and O(N/sub t/N/sub s/) memory resources when analyzing electromagnetic wave interactions with uniformly meshed planar structures. Here, N/sub t/ and N/sub s/ are the numbers of simulation time steps and spatial unknowns, respectively. The proposed scheme is therefore far more efficient than classical time-marching solvers, the CPU and memory requirements of which scale as O(N/sub t//sup 2/N/sub s//sup 2/) and O(N/sub t/N/sub s//sup 2/). In the proposed scheme, all pertinent time-domain half-space Green functions are (pre) computed from their frequency-domain counterparts via inverse discrete Fourier transformation. In this process, in-band aliasing is avoided through the application of a smooth and interpolatory window. Numerical results demonstrate the accuracy and efficiency of the proposed algorithm.     

基于业务的传送网故障测度新方法

提出了一个基于业务的传送网四元组故障测度方法(O,A,P,R)。为测度故障对网络造成的实际损失和潜在影响程度,提出了两个量化评价指标:业务中断指数和业务影响指数。通过连接离散的评价值,得到两个时变的连续评价函数。对该两个函数在故障时间上积分,得到量化的测度结果。四元组分别从实际损失、潜在影响、过程变化、相关信息等四个方面对结果进行描述。以某实际网络的一部分为样例环境,对该方法和其它方法的测度结果进行了对比。结果显示无论在单故障还是多故障场景下,该方法的效果都优于作对比的方法。     

Power Modeling and Efficient FPGA Implementation of FHT for Signal Processing

Fast Hadamard transform (FHT) belongs to the family of discrete orthogonal transforms and is used widely in image and signal processing applications. In this paper, a parameterizable and scalable architecture for FHT with time and area complexities of O(2(W+1)) and O(2N²), respectively, has been proposed, where W and N are the word and vector lengths. A novel algorithmic transformation for the FHT based on sparse matrix factorization and distributed arithmetic (DA) principles has been presented. The architecture has been parallelized and pipelined in order to achieve high throughput rates. Efficient and optimized field-programmable gate array implementation of the proposed architecture that yield excellent performance metrics has been analyzed in detail. Additionally, a functional level power analysis and modeling methodology has been proposed to characterize the various power and energy metrics of the cores in terms of system parameters and design variables. The mathematical models that have been derived provide quick presilicon estimate of power and energy measures, allowing intelligent tradeoffs when incorporating the developed cores as subblocks in hardware-based image and video processing systems     

Bits-per-Joule Capacity of Energy-Limited Wireless Networks

For a wireless network in which every node is bounded in its energy supply, we define a new concept of network capacity called "bits-per-Joule capacity", which is the maximum total number of bits that the network can deliver per Joule of energy deployed into the network. For a fixed network size, a finite number of information bits is delivered for each source-destination pair, under a fixed end-to-end probability of error constraint. We prove that under the one-to-one traffic model in which every node wants to send traffic to a randomly chosen destination node, the bits-per-Joule capacity of a stationary wireless network grows asymptotically as Omega((N/logN)^(q-1)/2 ), where N is the number of nodes randomly deployed onto the surface of a sphere and q is the path loss exponent. Further, the length of the block codes used grows only logarithmically in N, which indicates manageable decoder complexity as the network scales. The fact that the bits-per-Joule capacity grows with the number of nodes contrasts sharply with the scaling laws that have been derived for throughput capacity and implies that large-scale deployments for energy-limited sensor and ad hoc networks may be suitable for delay-tolerant data applications     

基于FPGA的ARINC-429总线收发系统实现

在高速率的ARINC-429通信中,采用传统的单片机控制方式已很难满足系统速率要求.文中介绍了利用FPGA(现场可编程门阵列)的高速、灵活性来控制HS-3282芯片,实现了ARINC-429总线串码的实时接收与发送,系统采用工业计算机PC104控制收发通道、发送次数、波特率等参数,并实时显示收发信息,实现了人机交互.     

Matrix Factorizations for Parallel Integer Transformation

Integer mapping is critical for lossless source coding and has been used for multicomponent image compression in the new international image compression standard JPEG 2000. In this paper, starting from block factorizations for any nonsingular transform matrix, we introduce two types of parallel elementary reversible matrix (PERM) factorizations which are helpful for the parallelization of perfectly reversible integer transforms. With improved degree of parallelism and parallel performance, the cost of multiplications and additions can be, respectively, reduced to O(logN) and O(log²N) for an N by N transform matrix. These make PERM factorizations an effective means of developing parallel integer transforms for large matrices. We also present a scheme to block the matrix and allocate the load of processors for efficient transformation     

基于改进型巴特勒矩阵的短波8元圆环阵列多波束技术研究

传统短波接收天线为单一的波束指向天线或全向天线。为提高接收天线增益,同时产生多个波束指向不同方向,提出利用巴特勒矩阵作为短波接收天线阵的无源波束形成网络。在传统8×8巴特勒矩阵结构的基础上,设计改进型8×8巴特勒矩阵。以均匀8元圆环阵列为天线模型,利用FEKO仿真分析了其天线特性。在3~11 MHz频段内,P2、P3、P6、P7四个端口分别在202.5°、292.5°、112.5°、22.5°方向上得到了方向性较强的单一波束,7 MHz时波束增益达到最大11.9 dBi,波瓣3 dB宽度平均为60°;在P1、P4、P5、P8端口产生相同的2个波瓣,7 MHz时其波束增益达到最大9.8 dBi,波瓣3 dB宽度平均为89°。由以上仿真分析得出,该改进型8×8巴特勒矩阵能够同时产生6个波束,波束覆盖8个方向,提高了波束的方向性,提高了天线增益。