Extended Monte Carlo localization algorithm for mobile sensor networks

A real-world localization system for wireless sensor networks that adapts for mobility and irregular radio propagation model is considered. The traditional range-based techniques and recent range-free localization schemes are not well competent for localization in mobile sensor networks, while the probabilistic approach of Bayesian filtering with particle-based density representations provides a comprehensive solution to such localization problem. Monte Carlo localization is a Bayesian filtering method that approximates the mobile node＇s location by a set of weighted particles. In this paper, an enhanced Monte Carlo localization algorithm-Extended Monte Carlo Localization （Ext-MCL） is proposed, i.e., the traditional Monte Carlo localization algorithm is improved and extended to make it suitable for the practical wireless network environment where the radio propagation model is irregular. Simulation results show the proposal gets better localization accuracy and higher localizable node number than previously proposed Monte Carlo localization schemes not only for ideal radio model, but also for irregular one.     

基于改进地形重构的SSPE传播预测方法

针对复杂环境下电波传播预测分析难的问题,提出了一种基于地形重构的分步抛物方程(split-step parabolic equation, SSPE)传播预测方法. 该方法采用具有广角传播因子且步长可变的双向SSPE解法,并利用基于改进地形重构的SSPE传播预测方法对真实地形的电波传播特性进行仿真分析和试验验证. 与现有的电波传播预测方法相比,该方法结合了真实地形,通过改进重构算法对地形建模效果进行完善,并利用变步长双向SSPE解法进行传播损耗的预测. 仿真试验结果表明,此预测方法6 dB以内的精度满足了高精度电波传播模型的要求,表明该方法具有实际意义与推广价值.     

典型场景下电波传播特性建模

为了解决某些典型场景(如海上、山区、丘陵、城区)下无法使用已有基础模型来全面表达电波传播特性的问题,建立了一种在典型场景下,基于确定性抛物方程、适用于多个传输场景的统一电波传播模型。把典型场景等效为损耗介质层来求解边界条件,利用Fourier分步步进法得到相应解,然后得到电波在典型场景下的传播损耗,并进行了理论分析和实验验证。结果表明,在不同传输场景下,将统一电波传播模型与Miller-Brown模型、射线追踪模型进行比较,结果较吻合,验证了其正确性。这一结果对建立一种求解典型场景下电波传播衰落问题的统一电波传播模型是有帮助的。     

PE模型预测蒸发波导中电波传播损耗

针对电磁波在蒸发波导中的异常传播现象,研究了电磁波在蒸发波导中的传播损耗,其传播损耗是电波传播的一个重要概念,并受到广泛关注。抛物模型(PE,Parabolic Equation Model)作为目前研究电波传播的主要模型,通过与Two-ray模型的对比分析验证了PE模型的可行性,且PE模型计算电磁波的传播损耗时可以克服其他模型预测粗糙海面时的不足。仿真分析表明,电波在蒸发波导中传播时的损耗值比在标准大气中的损耗值要小。     

Measurement, modeling, and simulation of digital LOS microwavechannels with applications to outage prediction

A summary of prior work in the field of microwave line-of-sight (LOS) channel propagation measurements, channel models, and channel simulators is presented. The objective of these efforts is the reliable prediction of digital microwave radio performance on any specified link. Many digital radio outage prediction techniques are predicted upon the use of m-curves, which characterize a digital radio's performance in a simulated fading environment. These m-curves are generated by subjecting the radio under test to simulated multipath fading. This requires the use of a channel simulator that accurately emulates the fading conditions found on real LOS links. All parameters of an ideal channel simulator should be based on a model that has been validated through propagation measurements on a number of different paths. Although much progress has been made, some issues remain for further investigation. New channel propagation measurement, modeling, and simulation results that are directly applicable to these issues are given     

城市微区多径色散传播信道的数学模型分析

城市微蜂窝移动无线电信道的传播特性相当复杂，因此如何建立这种信道的传播模型无论对理论分析还是对网络工程应用来说都是非常重要的，本文在分析讨论多径色散信道基本特征的基础上，对反映城市微蜂窝移动无线电信道传播特性的一些重要特征函数的数学模型进行了较为系统的分析和研究，并对一些重要模型进行了计算机仿真。     

基于PE模型的电波传播特性预测技术研究

PE模型已经被广泛地应用于电波传播特性预测技术的研究,并成为解决电波传播问题的主要工具。通过对抛物方程推导过程中由于对伪微分算子Q的处理而产生的误差进行分析,表明PE模型在预测小仰角的电波传播时具有很好的计算精度。对基于PE模型的电波传输损耗理论模型进行计算机仿真,得到电波传播损耗的理论计算值,通过与实测数据进行对比,验证了PE模型用于电波传播特性预测的正确性,并且对理论模型的计算结果稍微偏小的原因做了分析。     

宏小区无线电波传播预测模型仿真分析

无线电波传播模型主要用于计算无线电波传播路径损耗中值.针对宏小区无线电波传播需要考虑地形、环境类型以及构成环境的材料等各方面因素,研究了奥村经验模型中参数的算法和取值,用MATLAB仿真依据线性回归校正算法校正奥村经验模型.仿真结果表明,在频率一定的情况下,随着收发距离d的增加,电波传播路径损耗也增大;建筑物的密度越大,电波传播路径损耗越大.仿真结果与实际环境测试数据一致,也验证了校正的奥村经验模型的可靠性.     

Survey of ICIC techniques in LTE networks under various mobile environment parameters

LTE networks’ main challenge is to efficiently use the available spectrum, and to provide satisfying quality of service for mobile users. However, using the same bandwidth among adjacent cells leads to occurrence of Inter-cell Interference especially at the cell-edge. Basic interference mitigation approaches consider bandwidth partitioning techniques between adjacent cells, such as frequency reuse of factor m schemes, to minimize cell-edge interference. Although SINR values are improved, such techniques lead to significant reduction in the maximum achievable data rate. Several improvements have been proposed to enhance the performance of frequency reuse schemes, where restrictions are made on resource blocks usage, power allocation, or both. Nevertheless, bandwidth partitioning methods still affect the maximum achievable throughput. In this proposal, we intend to perform a comprehensive survey on Inter-Cell Interference Coordination (ICIC) techniques, and we study their performance while putting into consideration various design parameters. This study is implemented throughout intensive system level simulations under several parameters such as different network loads, radio conditions, and user distributions. Simulation results show the advantages and the limitations of each technique compared to frequency reuse-1 model. Thus, we are able to identify the most suitable ICIC technique for each network scenario.     

Mm-wave indoor radio channel modelling vs. measurements

A propagation model for the prediction of indoor radio channel characteristics at millimetre-wave frequencies, based on geometrical optics is described. This model has been shown to agree well with wide-band measurements carried out at Eindhoven University of Technology [8]. Simulation results for 4th and 6th order reflection are compared with corresponding measured data obtained in small and medium size rooms. The influence of objects located inside the room superstructure, on the indoor radio channel characteristics, is analysed. The agreement between measured and simulated results, confirms the validity of the proposed simulation method.J.J.G. Fernandes would like to thank JNICT — Portugal, for sponsorship.     

一种新的应用于并行数字仿真的电路划分算法

为减少仿真的时间,并行仿真技术广泛应用于大规模集成电路的计算.研究发现为并行仿真所做的电路划分对提高仿真速度有相当重要的作用.该文提出一个新的多层启发式的拓扑电路划分算法,展示了将该算法应用于一个实际的电路并行仿真系统(Discovery)所获得的仿真加速.该算法主要着眼于平衡计算负载,减少整个仿真网络通信量这两方面来提高仿真系统的性能.试验结果表明该算法比其他的电路划分算法取得了更好的性能提高.     

Cluster analysis preprocessor for path loss modelling using neuralnetworks

The neural networks technique is applied to model path loss of indoor radio propagation. Cluster analysis is employed as a preprocessor to simplify the characterisation of the complicated indoor environment. Simulation results demonstrate that this method is feasible, resulting in a substantial reduction of data input requirement     

A method for estimating local traffic load in a simulcast radiosystem

This paper presents a simple method for estimating the average local traffic load in a simulcast radio system. Such estimation is crucial to achieving efficient resource sharing and dynamic reconfiguration of the simulcast areas. The proposed method is based only on relative power measurements at each radio port (or distributed antenna element) and is applicable to both code-division multiple-access (CDMA) and time-division multiple-access (TDMA) systems. Simulation results are derived to test the method over various system conditions and assumptions. The proposed method is shown to provide excellent results, giving estimates to within ±15% of the actual Erlang traffic, while requiring only an approximate knowledge of the radio propagation environment     

Effects of antenna sectorisation on data rate limitations of indoor radio modems

A deterministic model of indoor radio propagation that uses ray tracing techniques is introduced. This model is suitable for analysing the performance of sector antenna systems in an indoor radio environment. Using this model, the effects of sectorisation of the antenna on the data rate limitations of BPSK and BPSK/DFE modems, operating in an indoor radio channel are analysed.<>     

A Simplified Method for Prediction of Multipath Fading Outage of Digital Radio

We propose a simplified method based on the correlated Rayleigh probability distribution of in-band radio signals. It can be efficiently applied to the calculation of the outage for various radio path length, propagation terrain, radio frequency, bandwidth, and digital modulation techniques. Predicted results are compared to various propagation data.     

A flexibly configurable spatial model for mobile radio channels

The application of multiple directive antennas, i.e., directional diversity, may lead to significant capacity benefits in cellular mobile radio systems. A flexibly configurable statistical channel model for mobile radio systems using directional diversity is presented. The parameters of this model, which is available as a FORTRAN77 program, can be easily adjusted to various propagation areas such as, for example, rural, urban, microcellular, and picocellular environments. Therefore, the model is well suited to perform simulations, evaluations, and comparisons of mobile radio systems. Simulation results concerning a code-division multiple-access (CDMA) mobile radio system which uses multiple directive base station (BS) antennas in combination with joint detection illustrate the application of the presented channel model     

战场环境中的电波传播模型优化选择方法

针对战场级的复杂电磁环境仿真过程中涉及到全频段覆盖、环境影响、仿真速度要求高等问题,提出了一种综合考虑用频装备、环境信息和模型自身特点的电波传播模型选择方法。该方法首先通过频段对用频装备及电波传播模型进行划分,再结合环境信息中降雨量、海拔、植被覆盖率、气候类型、导电特性等参数进行综合分析,最终得到传播模型的优化选择方案。在典型作战场景仿真应用中,该方法为传播模型的合理选择提供了思路,保证了仿真的精度,同时也为电磁环境仿真中传播模型本地化提供了依据。     

Characterisation of mobile velocity in GSM using a simplefeed-forward neural network

A neural network based approach for the characterisation of mobile velocity in GSM is investigated, using signal strength measurement reports of mobiles in active mode. Simulation results are very encouraging. The proposed method is computationally simple and yields consistent results for a wide range of mobile radio propagation parameters