The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper investigates how the temporal response and spatial fading statistics for mobile-to-mobile links in hilly and mountainous terrain depend on terrain variations. Fading statistics are generated from Monte Carlo simulations using several terrain databases. These simulations employ a computer code that accounts for diffraction over terrain obstacles and for non-specular scattering from terrain...
In this paper, we compare the two most common types of statistical models for V2V channels: the tapped-delay line, and the geometry-based stochastic model. We first provide a description of each model type. Model adaptations and options are described, as is model flexibility, and ability to replicate statistics that agree with measurements. We quantify each model's complexity, and show that the modified...
System-level simulations of packet-based orthogonal frequency-division multiple access (OFDMA) cellular networks require a proper consideration of the channel-dependent fast fading/scheduling in order to produce meaningful results. However, generating the time and frequency selective fast fading channels and performing detailed channel-adaptive scheduling for each user in a multi-cellular system is...
In this paper, we review the state of the field on measurements, models, and analysis for the vehicle-to-vehicle (V2V) channel. We first provide a survey of existing work on V2V models, including analytical and empirical models, and note main features and findings. Remaining work to be done in V2V modeling is then described, beginning with the logical next steps, then addressing less obvious areas...
A stochastic multiple-input multiple-output (MIMO) wireless channel model is discussed and its implementation scheme is proposed. An improved shaping-filter method, which can eliminate correlation of different paths by adding a random phase-shift and obtain the tap coefficient by using a double interpolation method, is proposed to simulate the MIMO fading channel. Simulation of 3GPP standard model...
This paper presents computationally efficient channel models, considered specifically from the point-of-view of network-level simulations. We outline models applicable at various system protocol layers of wireless communication systems, which take into account small-scale fading channel environments, and the time-variant error behavior relevant for mobile receivers. The presented models can be utilized...
A low-complexity hardware implementation method is proposed for discrete-time frequency-selective Rayleigh fading channels. The proposed method first employs the sum-of-sinusoids method to generate multiple independent flat fading channel responses, then utilizes a simple weight-delay-sum filtering method to incorporate the fractionally-delayed multipath rays into inter-tap correlated tap gains. It...
A stochastic 2times2 MIMO wideband channel modelling method is presented. This channel model uses tapped delay lines (TDL) to model the subchannels and a single channel spatial correlation matrix to introduce the statistical dependence. This model represents a novel simplification with respect to other wideband MIMO models. The channel models obtained from this method are accurate and computationally...
The Stochastic Tap Delay line model of the UWB indoor channel have been used for generating Power Delay Profile (PDP). The local Power Delay profiles for different categories of channel types with range of T-R distance separation as per IEEE 802.15.4a standard have been generated. The important attributes of PDP have been selected for investigating the relative Channel behavior. The Complementary...
In this paper we evaluate the influence of radio propagation modeling on VoIP quality in wireless network simulations. How propagation modeling can influence classification of strategies concerned in improving VoIP quality? We analyze reactive AODV and proactive OLSR approaches in a simulated 802.11 mesh backbone and calculate the VoIP quality by means of a reviewed version of ITU-TE-Model. Results...
In this paper we propose a VoIP study case to evaluate the impact of different radio propagation models on performance parameters of application layer in simulation studies of Wireless Mesh Backbones. For each presented model, we carried out experiments taking into account the credibility aspects suggested by simulation theory of stochastic processes. Results showed that, for the same scenario, using...
Recently, MIMO techniques have been using in active radars,and become a hot topic in radar field, where they improve the performance of detection and parameters estimation greatly. On estimates of direction-of-arrival (DOA) in active radars, generally elements of the receive array were closely spaced to enable direction finding measurements. However, in order to obtain angular diversity, all elements...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
In this paper userspsila short-term delay and throughput fundamental properties under basic opportunistic scheduling policies, required to support high throughput wireless communication systems with integrated multimedia services, are studied. Among the objectives of this work is to determine at what extent opportunistic scheduling policies can be used to support real-time services in addition to...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
In this paper, we study bandwidth management of a wireless/optical based access/metro network in support of voice and data services. For voice services, we use a finite state Markov Chain to estimate the blocking probability of voice circuits over an Adaptive modulation and coding wireless channel, as a function of the channel parameters. For data services, we evaluate a rate matching and a buffer...
This paper addresses adaptive channel estimation for time-varying mobile wireless channels with nonstationary statistics. We presents a reduced complexity adaptive channel estimator based on a set membership filtering approach known as the Optimal Bounding Ellipsoid (OBE) algorithm. To exploit time and frequency domain correlation properties of the channel in an efficient low-complexity way, we allow...
This paper investigates the effective gain of antennas in indoor channels. A metric called instantaneous effective gain is proposed, and a multiple-cluster 3D channel model is used to facilitate the proposed antenna effective gain. In the multiple-cluster channel model, Laplacian and double exponential distribution are utilized to model azimuth and elevation signal power distribution respectively,...
In this paper, we consider a new channel probing scheme for opportunistic scheduling in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the probing, we consider a two-step channel probing process; called pre-probing and mainprobing. Good subchannels are first estimated through the pre-probing process using a probing signal transmitted...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.