A new path loss prediction statistical model for indoor wireless communications

A statistical model for path loss prediction for indoor wireless communication systems, based on the Incomplete Gamma Distribution is developed. Two different approaches of the same path loss model are studied for proving the modularity and the flexibility of the proposed statistical model. Comparison with already published measurements is carried out, ensuring the better adaptability of the proposed model.     

Time-series model for wireless fading channels in isotropic and nonisotropic scattering environments

An autoregressive (AR) model is presented for isotropic and nonisotropic scattering environments characterized by Rice factor 0/spl les/K相似文献   

A simplified analytical model for predicting path loss in urban andsuburban environments

An analytical propagation model has recently been developed to predict radio signal attenuation in urban and suburban environments. This analytical model explicates the path loss as a result of signal reduction due to free space wavefront spreading, multiple diffraction past rows of buildings, and building shadowing. It is applicable for cellular mobile services as well as personal communications services (PCS) in both macro- and microcellular environments. Good accuracy was found for this analytical model by comparing the predictions with numerous measurements made in various propagation environments. However, since the analytical model involves multiple-dimension integration to calculate the signal attenuation due to multiple diffraction past rows of buildings, the model in its original format does not lend itself to easy implementation into a radio system planning tool. A simplified version of the analytical model is developed in this paper, which can be used for three different propagation scenarios with base-station antenna above, below, and near the average rooftop level     

Propagation models for short-range wireless channels with predictable path geometries

We consider wireless data services characterized by short distances, no shadowing, low power, and low antenna heights, deployed in places where a high frequency of potential users is expected, e.g., toll booths, parking lots, intersections, etc. Within such a system, we expect to see a well-defined geometry of base-to-user radio paths, as well as a predictable user trajectory, neither of which can be assumed for the wide-area cellular case. This offers the promise of a strong deterministic component of the channel response, in addition to a weaker stochastic component. Here, we combine analysis of the former with measurements and modeling of the latter for three typical outdoor scenarios. Comparisons between predicted and measured behavior show excellent agreement.     

Effect of terrain on path loss in urban environments for wirelessapplications

Path loss prediction algorithms for advanced wireless communication system planning have long considered the effect of electromagnetic propagation over buildings between the base station and subscriber. This phenomena is particularly important in residential areas, where the houses are typically a few stories high. For the most part, the buildings were assumed to lie on level terrain, although shadowing effects by the terrain in the absence of buildings has been included. Previous works have offered a number of methods to quantitatively determine these effects from path profiles. This study examines propagation over buildings when the buildings are located on terrain features (hills). The buildings, which are represented by a series of absorbing half screens, are assumed to lie in rows that are equally spaced along parallel streets, with the streets running perpendicular to the terrain slope. Numerical results are obtained using successive repetition of the Kirchhoff-Huygens approximation. A phenomenological model based on ray optics for diffraction over a smooth surface is proposed as a way to interpret the numerical results. The dependence of the model coefficients on the terrain parameters are obtained from the numerical results     

Non-line-of-sight ultraviolet single-scatter path loss model

A novel non-line-of-sight ultraviolet single-scatter path loss model for coplanar geometries is proposed on the basis of spherical coordinate system. In comparison with the classical single-scatter analytical model based on the prolate-spheroidal coordinate system, it is of a simple integral form which only depends on the variables of the zenith and receiver elevation angles. Additionally, analytical approximation for the proposed single-scatter path loss model is presented. Numerical examples on path loss are presented for various system geometries. Correspondingly, the results are verified with the classical single-scatter analytical model, which demonstrates the validity of our path loss model and the reasonability of the analytical approximation.     

A stochastic multipath channel model including path directions for indoor environments

A novel stochastic channel model for the indoor propagation channel is presented. It is especially for, but not limited to future communication systems with multiple antennas like space division multiple access (SDMA), spatial filtering for interference reduction (SFIR), or multiple-input/multiple-output (MIMO). The model is designed for indoor scenarios, straight forward extendable to urban environments. It is based on physical wave propagation. The new approach describes the channel by multipath components, each characterized by its transfer matrix (including loss), delay, direction of arrival, and departure. The appearance and disappearance of multipath components over time is modeled as a birth and death process, a marked Poisson process. This enables first-time the correct modeling of spatial and temporal correlations. In each modeling step, path properties change according to the motion of transmitter and receiver. The changing delay times of propagation paths yield a realistic Doppler behavior of the channel. Deterministic ray tracing results are used to produce the huge data sets required for the statistical evaluation of the parameters of the proposed model. This method enables an automated parameter extraction for new environments or frequencies. The ray tracing tool has been verified by narrowband, wideband, and directional channel measurements. The novel stochastic spatial channel model allows the simulation of third-generation broadband radio systems including arbitrary antenna configurations and patterns. System simulations for the bit-error rate of radio links can be performed including intelligent antenna configurations like SDMA, SFIR, or MIMO. Furthermore, the capacity of complete systems can be investigated.     

A physical scattering model for MIMO macrocellular broadband wireless channels

This paper presents a physical scattering model that predicts multiple-input multiple-output (MIMO) channel characteristics conforming well to experimental observations in macrocells. Our approach is to start with a given single-input single-output power-delay profile (defined for specific range, bandwidth and antenna parameters) and fit a scattering model that characterizes the MIMO channel. From the derived scattering model and antenna array configurations, the MIMO channel is computed using a ray-based method. Simulations of several MIMO channels are shown to exhibit experimentally observed channel correlations, antenna beamwidth effect, range dependency, and frequency selectivity.     

基于节点安全预测的火场撤离路径规划

火场烟雾弥漫、能见度低,消防队员很难准确定位并找寻到合适的撤离路径.文中使用人机协作在火场中建立动态三角网基础上,以网络节点为参考点为消防员规划撤离路线.该方案使用基于相似函数的证据理论对火场中各节点采集的烟雾浓度、温度、氧气浓度进行数据融合,并确定节点位置的安全等级;引入预测机制,可以预测短时间内前进路径中节点位置的安全等级的变化.根据安全等级变化,剔除网络中危险节点,使用基于路程换算的A算法计算实时最短的安全路径.通过数据分析表明,该方案能更好的适应火场环境多变的特点.     

Path loss model for wireless narrowband communication above flat phantom

A new empirical path loss model for wireless communication at 2.4 GHz above a flat, lossy medium, representing human tissue, is presented. The model is valid for dipole antennas for heights up to 5 cm above the phantom and for distances up to 40 cm, and was applied to muscle and brain simulating media. For antennas placed close to the lossy medium, it was found that antenna height has a major influence on path loss. The model has been validated by measurements and simulations, which show excellent agreement     

基于PCNN的迷宫最短路径求解算法

本文根据脉冲耦合神经网络(PCNN)并行运行的特点,提出了基于PCNN模型的迷宫最短路径搜索算法。从理论上对该算法进行了分析和讨论,并给出了具体的算法和实验结果,验证了该方法的有效性。与其他算法相比,该方法可以在最短的时间内完成最短路径的搜索。     

无线移动信道的仿真模型分析

通过对无线移动信道衰落特性的分析，建立了数学模型和计算机仿真模型，并对计算机仿真结果进行了分析，得出了相应结论。     

New path planning model for mobile anchor-assisted localization in wireless sensor networks

As event detection is one of the main purposes of using wireless sensor networks (WSNs), the nodes location is essential to determine the location of that event when it occurs. Many localization models have been proposed in the literature. One of the solutions is to deploy a set of location-aware nodes, called anchors, to exchange information with the other nodes in order to help estimate their own location. Another promising proposal involves replacing these sets of anchors with only one mobile anchor. While this proposal seems to provide favorable results, it brings new challenges. The main challenge is to find an optimal path for the mobile anchor to follow while taking into account the need to provide highly accurate data and more localizable nodes in less time and with less energy. In this paper, we introduced a new static path planning model for mobile anchor-assisted localization in WSNs. Our proposed model guarantees that all nodes are able to receive the localization information, thus, estimate their own location with higher localization accuracy in comparison to similar static models. Moreover, this model overcomes the problem of collinearity and takes into account the metrics of precision and energy consumption as well as accuracy, localization ratio and the path length of the mobile anchor.     

A model for the multipath delay profile of fixed wireless channels

This paper deals with the measurement and modeling of multipath delay on fixed wireless paths at 1.9 GHz in suburban environments. The primary focus is on the delay profile, which is the normalized plot of received power versus delay in response to an RT “impulse.” We describe measurement campaigns in the western suburbs of Chicago, IL, and in suburban north-central New Jersey. Our analysis of the data suggests to us that, for directive terminal antennas, the delay profile can be modeled as having a “spike-plus-exponential” shape, i.e., a strong return (“spike”) at the lowest delay, plus a set of returns whose mean powers decay exponentially with delay. This delay profile can be characterized by just two parameters (both variable over the terrain), namely, the ratio (K₀) of the average powers in the “spike” and “exponential” components and the decay time constant (τ₀) of the “exponential” component. No such simple structure appears to apply for delay profiles using omnidirectional antennas. For a directive antenna with a 32° beamwidth, we find that: (1) the statistical correlation between the profile parameters K₀ and τ₀ is negligible; (2) these parameters are relatively insensitive to antenna height and path length; and (3) over each measured region (Illinois and New Jersey), K₀ and τ₀ have median values close to 8 dB and just below 0.2 μs, respectively. Moreover, we have found simple probability distributions that accurately portray the variability of K₀ and τ₀ over the terrain     

EPTR: expected path throughput based routing protocol for wireless mesh network

For effective routing in wireless mesh networks, we proposed a routing metric, expected path throughput (EPT), and a routing protocol, expected path throughput routing protocol (EPTR), to maximize the network throughput. The routing metric EPT is based on the estimated available bandwidth of the routing path, considering the link quality, the inter- and intra-flow interference and the path length. To calculate the EPT of a routing path, we first calculate the expected bandwidth of the link and the clique, and then consider the decay caused by the path length. Based on EPT, a distributed routing protocol EPTR is proposed, aiming to balance the network load and maximize the network throughput. Extensive simulations are conducted to evaluate the performance of the proposed solution. The results show that the proposed EPTR can effectively balance the network load, achieve high network throughput, and out-perform the existing routing protocols with the routing metrics previously proposed for wireless mesh networks.     

基于环境模型的移动机器人路径规划

介绍了一种新的移动机器人路径规划方法。采用链接图法,对工作空间建模。用Dijkstra算法决策出全局最短路径,然后用遗传算法对此路径进行优化,得到全局最优路径。最后提出了一种对路径几何改进的方法。仿真结果表明,该方法方便简单,对所规划的路径质量有所提高。     

基于进化神经网络的地空路径雨衰减模型

雨衰减对工作在高频的地空通信链路稳定性具有很大影响。本文在考虑多个参数对雨衰减非线性影响的基础上,建立了基于进化神经网络的雨衰模型,并与ITU－R模型进行了比较。结果表明,利用本文提出的模型进行高频电波的预测具有更好的精度,可降低平均误差0.64dB,并减小标准偏差0.79bD,为雨衰减预测提供了一种新的方法。     

A generic model for MIMO wireless propagation channels in macro- and microcells

This paper derives a generic model for the multiple-input multiple-output (MIMO) wireless channel. The model incorporates important effects, including i) interdependency of directions-of-arrival and directions-of-departure, ii) large delay and angle dispersion by propagation via far clusters, and iii) rank reduction of the transfer function matrix. We propose a geometry-based model that includes the propagation effects that are critical for MIMO performance: i) single scattering around the BS and MS, ii) scattering by far clusters, iii) double-scattering, iv) waveguiding, and v) diffraction by roof edges. The required parameters for the complete definition of the model are enumerated, and typical parameter values in macro and microcellular environments are discussed.