Sanjay Soni

Time-Domain Solution for Transmitted Field Through Low-loss Dielectric Obstacles in a Microcellular and Indoor Scenario for UWB Signals

An analytical time-domain (TD) solution based on an established frequency-domain (FD) transmission model is presented for transmission of ultrawideband (UWB) signals through low-loss dielectric obstacles, in a microcellular and indoor propagation environment. This paper provides an in-depth analysis of the FD transmission model and presents a computationally more efficient direct TD transmission solution. Various obstacles considered in this paper include dielectric wedge and rectangular building with homogeneous, isotropic, and low-loss dielectric characteristics. Novel TD transmission coefficients, for transmission through an interface between air and a low-loss dielectric medium, are proposed for both hard and soft polarizations. The proposed TD solution is validated against the numerical inverse fast Fourier transform of the exact FD (IFFT-FD) solution and the results are found to be in very good agreement with each other. The computational efficiency achieved through the proposed TD solution is demonstrated by comparing its computation time with that of the exact IFFT-FD solution.

A Probabilistic Analysis of Path Duration Using Routing Protocol in VANETs

In recent years, various routing metrics such as throughput, end-to-end delay, packet delivery ratio, path duration, and so forth have been used to evaluate the performance of routing protocols in VANETs. Among these routing metrics, path duration is one of the most influential metrics. Highly mobile vehicles cause frequent topology change in vehicular network environment that ultimately affects the path duration. In this paper, we have derived a mathematical model to estimate path duration using border node-based most forward progress within radius (B-MFR), a position based routing protocol. The mathematical model for estimation of path duration consists of probability of finding next-hop node in forwarding region, estimation of expected number of hops, probability distribution of velocity of nodes, and link duration between each intermediate pair of nodes. The analytical results for the path duration estimation model have been obtained using MATLAB. The model for path duration estimation has been simulated in NS2. Each of the analytical results has been verified through respective simulation results. The result analysis clearly reveals that path duration increases with the increase in transmission range and node density and decreases with the increase in the number of hops in the path and velocity of the nodes.

A New Time-Domain Solution to Transmission Through a Multilayer Low-Loss Dielectric Wall Structure for UWB Signals

In this work the time-domain solution for transmission through a multilayer wall structure has been presented. A time-domain transmission coefficient formulation for transmission through an interface between two low-loss dielectric mediums with different electrical properties is derived. Both hard and soft polarizations are considered. A novel ray tracing algorithm for multilayer wall structure has been presented with accuracy of ray-traced path as close as order of

A New Closed-Form Expressions of Channel Capacity with MRC, EGC and SC Over Lognormal Fading Channel

10^{-5}

A comparison between transmitted and diffracted field in a microcellular scenario for UWB signals

10-5. Further, in depth formulation for actual refracted angles for different layers of the wall has been presented and exact frequency-domain formulation for transmitted field at the receiver has been obtained. The exact formulation has been simplified under the condition of low loss assumption and this simplified formulation has been converted to time-domain formulation using inverse Laplace transform. The proposed time-domain solution has been validated with the inverse fast Fourier transform of the corresponding exact frequency-domain solution. Further the computational efficiency of both the methods has been compared.

Performance of an energy detector over η-μ/lognormal composite channel with cooperative sensing

The presence of both the fading and shadowing effects (also called composite multipath/shadowed fading) is often encountered in a realistic radio propagation scenario, thus, making it necessary to consider the simultaneous effect of fading and shadowing on the received signal. The multipath effect is captured using models such as Rician, Nakagami-m, Weibull distribution and shadowing effect is modeled using Log-normal distribution. In this paper we present the closed-form expression of composite (Weibull/log-normal shadowed) fading using the efficient tool proposed by Holtzman. Using this result, the closed-form expression of combined (time-shared) shadowed/unshadowed fading is presented. The performance measures of fading communication systems such as probability density function of signal to noise ratio, amount of fading, outage probability (Pout) and channel capacity are analyzed and expressed in closed form.

Performance of MRC receiver over Hoyt-lognormal Composite Fading Channel

In this work, we derive the closed-form expressions of channel capacity with maximal ratio combining, equal gain combining and selection combining schemes under different transmission policies such as optimal power and rate adaptation, optimal rate adaptation, channel inversion with fixed rate (CIFR) and truncated CIFR. Various approximations to the intractable integrals have been proposed using methods such as Holtzman and Gauss–Hermite approximations and simpler expressions are suggested. Moreover, as an application, the channel capacity of lognormally distributed fading channel in the interference-limited environment is discussed. The obtained closed-form expressions have been validated with the exact numerical results.

A New Time-Domain Model for Multiple Scattering of UWB Signals Through Lossy Obstacles

A novel approach to predict field strength in the shadow of a 3-D building scenario is presented. The field strength predicted by the proposed model is compared with available measurements and earlier predicted fields based on Fresnel-Kirchhoff theory. Two different scenarios have been considered to validate our model. The proposed model gives an improvement of 7.7 dB for Scenario 1; and 5.8 dB for Scenario 2. A good agreement between the prediction and the measurement is also observed.