蜂房移动通信系统的信道下界

本文提出了蜂房移动通信系统中无三阶互调带宽信道数的下界公式。根据该公式得到最小带宽信道数。本文还给出了实际带宽信道数和无三阶互调信道组。     

Distance Reduction in Mobile Wireless Communication: Lower Bound Analysis and Practical Attainment

The transmission energy required for a wireless communication increases superlinearly with the communication distance. In a mobile wireless network, nodal movement can be exploited to greatly reduce the energy required by postponing communication until the sender moves close to a target receiver, subject to application deadline constraints. In this paper, we characterize the fundamental performance limit, namely the lower bound expected communication distance, achievable by any postponement algorithm within given deadline constraints. Our analytical results concern mainly the random waypoint (RWP) model. Specifically, we develop a tight analytical lower bound of the achievable expected communication distance under the model. In addition, we define a more general map-based movement model, and characterize its lower bound distance by simulations. We also address the practical attainment of distance reduction through movement-predicted communication. Specifically, whereas prior work has experimentally demonstrated the effectiveness a least distance (LD) algorithm, we provide an absolute performance measure of how closely LD can match the theoretical optimum. We show that LD achieves an average reduction in the expected communication distance within 62% to 94% of the optimal, over a realistic range of nodal speeds, for both the RWP and map-based models.     

Joint Particle Filter and UKF Position Tracking in Severe Non-Line-of-Sight Situations

The performance of localization techniques in a wireless communication system is severely impaired by biases induced in the range and angle measures because of the non-line-of-sight (NLOS) situation, caused by obstacles in the transmitted signal path. However, the knowledge of the line-of-sight (LOS) or NLOS situation for each measure can improve the final accuracy. This paper studies the localization of mobile terminals (MT) based on a Bayesian model for the LOS-NLOS evolution. This Bayesian model does not require having a minimum number of LOS measures at each acquisition. A tracking strategy based on a particle filter (PF) and an unscented Kalman filter (UKF) is used both to estimate the LOS-NLOS situation and the MT kinetic variables (position and speed). The approach shows a remarkable reduction in positioning error and a high degree of scalability in terms of performance versus complexity.     

一种适用于移动传感器网络的增强型蒙特卡罗定位跟踪算法

该文提出一种在低锚节点密度的移动传感器网络中实现定位跟踪的方法。利用受控的洪泛方式提高锚节点利用效率,采用遗传交叉操作加快预测阶段的抽样,采用插值方法对节点运动速度及方向进行预测,利用位置估计精度优于自身的1跳邻居节点的信息强化滤波条件。仿真实验结果表明,该文算法与传统算法相比加快了收敛速度,提高了定位精度,改善了在低锚节点密度时的性能。     

一种最大化系统用户速率下限的MIMO-MAC有限反馈干扰对齐算法

针对2小区MIMO-MAC中传统有限反馈干扰对齐码字选择方案的不足,本文提出了一种最大化用户速率下界的直接码字选择方案,并结合比特分配算法来减少和速率的损失,同时采用最大信干扰算法译码.不同于传统的基于最小弦距离或对齐度准则来选择码字,本文从最大化用户速率下界的角度来选择的码字;进一步地,在格拉斯曼空间中生成与期望预编码接近的码字集合,在该集合中只需简单的搜索便可找到优化的码字组合,同时实现了低复杂度和次优的全局搜索.仿真实验表明,相对于现有的典型算法,本文算法在提升系统和速率的同时,也提高了系统用户速率的下界.     

Statistical Modeling and Analysis of Mobile-to-Mobile Fading Channels in Cooperative Networks Under Line-of-Sight Conditions

Recently, mobile-to-mobile (M2M) cooperative network technology has gained considerable attention for its promise of enhanced system performance with increased mobility support. As this is a new research field, little is known about the statistical properties of M2M fading channels in cooperative networks. So far, M2M fading channels have mainly been modeled under the assumption of non-line-of-sight (NLOS) conditions. In this paper, we propose a new model for M2M fading channels in amplify-and-forward relay links, where it is assumed that a line-of-sight (LOS) component exists in the direct link between the source mobile station and the destination mobile station. Analytical expressions will be derived for the main statistical quantities of the channel envelope, such as the mean value, variance, probability density function (PDF), level-crossing rate (LCR), and average duration of fades (ADF) as well as the channel phase. Our results show that the statistical properties of the proposed M2M channel are quite different from those of double Rayleigh and double Rice channels. In addition, a high-performance channel simulator will be presented for the new M2M channel model. The developed channel simulator is used to confirm the correctness of all obtained theoretical results by simulations.     

面向移动用户的智能反射表面波束追踪与覆盖增强算法

虽然智能反射表面(IRS)单元可以通过改变相移和反射系数来增强系统性能,但是用户运动和时延等未知因素使反射波束无法准确覆盖用户。为此,提出一种面向移动用户的波束追踪与覆盖增强算法。首先,根据用户的初始位置、运动方向和速度等信息,估算IRS的目标覆盖区域;然后,对IRS单元进行分组,并设计不同分组单元的反射相移使反射波束指向目标区域的相邻位置,进而实现对用户可能位置的有效覆盖;最后,采用注水算法分配由基站(gNB)发射在IRS不同分组单元上的波束功率,实现对目标区域覆盖的增强。     

适用于Pbit/s光分组交换网络的丢包率下限模型

文章针对通过优化路由来改善光分组交换网络性能这一方法进行了深入地分析。文章认为在输出光缓存结构下可以计算出网络丢包率下限的理论模型,通过将该模型得到的丢包率下限与在已有路由算法下由仿真得到的丢包率进行比较,能够预测出最佳路由算法下的丢包率,从而进一步预测通过优化路由所能获得的最大性能提升。     

LOS/NLOS混合环境中的粒子滤波跟踪算法

扩展卡尔曼滤波算法在直达波(Line-Of-Sight,LOS)和非直达波(None-Line-Of-Sight,NLOS)混合环境中存在显著的误差。该文根据混合噪声概率密度函数的数值近似公式,提出了一种基于传播环境LOS/NLOS二元状态信息的粒子滤波算法。仿真结果表明,利用了二元环境信息和混合噪声密度的粒子滤波算法能明显改善对移动目标的跟踪估计精度。     

一种基于信标的移动卫通相控阵波束跟踪算法

提出并实现了一种利用卫星信标信号来实施基于相控阵天线的波束跟踪算法。该方法适用于采用相控阵天线技术的各种卫星"动中通"天线,克服了卫星信标信号强度弱,检测困难的弱点,提高了跟踪信噪比,同时采用了软件无线电方式解调可以提供最大的灵活性。跟踪算法的最大优点是没有任何陀螺仪的辅助,极大地提高了天线在各种极端运动环境下的适应能力。算法最终在自行研制的Ku波段相控阵移动卫星天线系统上获得验证。     

一种快速跟踪的单站无源定位算法

在单站无源定位与跟踪中，扩展卡尔曼滤波算法对初始值依赖性较强，在观测方程非线性较强时收敛速度和稳定性无法满足要求，因此文中提出了一种优先估计慢变化参量的定位跟踪算法，通过仿真比较验证了该算法具有较好的收敛速度和稳定性，具有对滤波初始值的依赖性小的优点。     

Paired Bernoulli Circular Spreading: Attaining the BER Lower Bound in a CSK Setting

This paper is concerned with the Paired Bernoulli Circular Spreading (PBCS), a way of generating optimal spreading for the single-user coherent chaos shift-keying (CSK) system. PBCS is optimal spreading in the sense that it attains the Bit Error Rate (BER) lower bound of the system, therefore it has a potential engineering impact on the choice of signal carrier in CSK communications. PBCS optimality is justified theoretically and is further demonstrated through BER simulations. The statistical properties of PBCS are of interest too, as it is an invariant stochastic process with a mixed joint density which allows to sample infinitely many points from a circle.     

分支界定法在特征向量提取中的应用

着重分析了基于搜索树和解数的分支界定算法在特征向量提取中的应用,阐述了搜索树的形成原理、解数的生成过程及可分性判据。通过matlab仿真,验证了该算法在特征提取应用中的有效性和合理性。     

Shakra: Tracking and Sharing Daily Activity Levels with Unaugmented Mobile Phones

This paper explores the potential for use of an unaugmented commodity technology—the mobile phone—as a health promotion tool. We describe a prototype application that tracks the daily exercise activities of people, using an Artificial Neural Network (ANN) to analyse GSM cell signal strength and visibility to estimate a user’s movement. In a short-term study of the prototype that shared activity information amongst groups of friends, we found that awareness encouraged reflection on, and increased motivation for, daily activity. The study raised concerns regarding the reliability of ANN-facilitated activity detection in the ‘real world’. We describe some of the details of the pilot study and introduce a promising new approach to activity detection that has been developed in response to some of the issues raised by the pilot study, involving Hidden Markov Models (HMM), task modelling and unsupervised calibration. We conclude with our intended plans to develop the system further in order to carry out a longer-term clinical trial.     

改进的主/被动传感器协同探测跟踪方法研究

针对主动传感器辅助的被动传感器跟踪系统,为了提升系统的跟踪精度,改进主动传感器工作控制的实时性和精确性,结合地空导弹武器跟踪系统中的"粗跟"与"精跟"模式,提出了一种改进的主/被动传感器协同探测跟踪方法。在主动传感器开机时,利用曲线拟合推理出目标的运动轨迹;关机后,利用拟合的"估计量测"值和滤波预测值产生新息残差,并将其作为评价因子,结合信息熵理论设计"粗跟"和"精跟"模式下的航迹质量评价准则。实现了主/被动传感器间的实时切换以及"粗跟"和"精跟"模式间的自适应切换,克服了被动传感器距离量测的不可观测性。采用Monte Carlo仿真,同跟踪门法作比较,结果验证了改进方法的合理性和优越性。     

Easy-hardware-implementation MMPF for Maneuvering Target Tracking: Algorithm and Architecture

In this paper, we present an easy-hardware-implementation multiple model particle filter (MMPF) for maneuvering target tracking. In the proposed filter, the sampling importance resampling (SIR) filter typically used for nonlinear and/or non-Gaussian application is extended to incorporating multiple models that are composed of a constant velocity (CV) model and a “current” statistical (CS) model, and the Independent Metropolis Hasting (IMH) sampler is utilized for the resampling unit in each model. Compared with the bootstrap MMPF, the proposed MMPF requires no knowledge of models and model transition probabilities for different maneuvering motions, and keeps a constant number of particles per model at all times. This allows a regular pipelined hardware structure and can be implemented in hardware easily. Furthermore, using the IMH sampler for the resampling unit avoids the bottleneck introduced by the traditional systematic resampler and reduces the latency of the whole implementation. Simulation results indicate that the proposed filter has approximately equal tracking performance with the bootstrap MMPF. Hardware architecture of the IMH sampler and its corresponding sample unit are presented, and a parallel architecture consisting of CV model processing element (PE), CS model PE and a central unit (CU) is described. The proposed architecture is evaluated on a Xilinx Virtex-II Pro FPGA platform for a maneuvering target tracking application and the results show many advantages of the proposed MMPF over existing approaches in terms of efficiency, lower latency, and easy hardware implementation.     

一种主/被动雷达协同探测跟踪模式及算法研究

为了提升地空导弹武器系统体系抗干扰及隐蔽性作战能力,结合新装备主动雷达和基于时差法测量的被动雷达系统各自技术优势,提出了一种主动雷达辅助的被动雷达协同探测跟踪模式,并针对该模式研究设计了一种协同探测跟踪算法。通过引入模糊推理函数,利用新息方差实际值和量测误差协方差变化率值作为模糊输入控制量,实时控制主动雷达的开关机工作,不仅实现了对主动雷达的精确化和实时化控制,而且提高了系统跟踪精度。通过Monte Carlo仿真,进一步验证了协同模式的合理性以及改进算法的有效性和正确性。     

Underwater Acoustic Networks: Channel Models and Network Coding Based Lower Bound to Transmission Power for Multicast

The goal of this paper is two-fold. First, to establish a tractable model for the underwater acoustic channel useful for network optimization in terms of convexity. Second, to propose a network coding based lower bound for transmission power in underwater acoustic networks, and compare this bound to the performance of several network layer schemes. The underwater acoustic channel is characterized by a path loss that depends strongly on transmission distance and signal frequency. The exact relationship among power, transmission band, distance and capacity for the Gaussian noise scenario is a complicated one. We provide a closed-form approximate model for 1) transmission power and 2) optimal frequency band to use, as functions of distance and capacity. The model is obtained through numerical evaluation of analytical results that take into account physical models of acoustic propagation loss and ambient noise. Network coding is applied to determine a lower bound to transmission power for a multicast scenario, for a variety of multicast data rates and transmission distances of interest for practical systems, exploiting physical properties of the underwater acoustic channel. The results quantify the performance gap in transmission power between a variety of routing and network coding schemes and the network coding based lower bound. We illustrate results numerically for different network scenarios.     

Mobile Coded Caching in Small Cell Networks: Algorithm Design and Performance Analysis

In coded caching, users cache pieces of files under a specific arrangement so that the server can satisfy their requests simultaneously in the broadcast scenario via e Xclusive OR(XOR) operation and therefore reduce the amount of transmission data. However, when users’ locations are changing, the uploading of caching information is frequent and extensive that the traffic increase outweighed the traffic reduction that the traditional coded caching achieved. In this paper, we propose mobile coded ...     

CORDIC算法在跟踪环中的应用与FPGA实现

主要介绍了坐标旋转数字计算（CORDIC）算法在跟踪环鉴别器中的应用,包括码跟踪环、锁频环和锁相环鉴别器,并进行了FPGA实现。在设计中,采用统一CORDIC算法优化方法减少硬件开销,用非流水方式在一个CORDIC运算基本单元中实现了码跟踪环、锁频环和锁相环三种鉴别器。同时对CORDIC运算的精度和位宽进行分析,在保证环路功能的情况下尽量减少硬件资源的使用。在Virtex5lx220上测试使用了该鉴别器的GPS跟踪环,取得了满意的跟踪效果。