Simulation Models with Correct Statistical Properties for Rayleigh Fading Channels

In this paper, new sum-of-sinusoids statistical simulation models are proposed for Rayleigh fading channels. These new models employ random path gain, random initial phase, and conditional random Doppler frequency for all individual sinusoids. It is shown that the autocorrelations and cross correlations of the quadrature components, and the autocorrelation of the complex envelope of the new simulators match the desired ones exactly, even if the number of sinusoids is as small as a single-digit integer. Moreover, the probability density functions of the envelope and phase, the level crossing rate, the average fade duration, and the autocorrelation of the squared fading envelope which contains fourth-order statistics of the new simulators, asymptotically approach the correct ones as the number of sinusoids approaches infinity, while good convergence is achieved even when the number of sinusoids is as small as eight. The new simulators can be directly used to generate multiple uncorrelated fading waveforms for frequency selective fading channels, multiple-input multiple-output channels, and diversity combining scenarios. Statistical properties of one of the new simulators are evaluated by numerical results, finding good agreements

Two new sum-of-sinusoids-based methods for the efficient generation of multiple uncorrelated rayleigh fading waveforms

This paper deals with the design of a set of multiple uncorrelated Rayleigh fading waveforms. The Rayleigh fading waveforms are mutually uncorrelated, but each waveform is correlated in time. The waveforms are generated by using the deterministic sum-of-sinusoids (SOS) channel modeling principle. Two new closed-form solutions are presented for the computation of the model parameters. Analytical and numerical results show that the resulting deterministic SOS-based channel simulator fulfills all main requirements imposed by the reference model with given correlation properties derived under two-dimensional isotropic scattering conditions. The proposed methods are useful for the design of simulation models for diversity-combined Rayleigh fading channels, relay fading channels, frequencyselective channels, and multiple-input multiple-output (MIMO) channels. © 2006 IEEE

A Statistical Simulation Model for Mobile Radio Fading Channels

Recently, a Clarke\u27s model-based simulator was proposed for Rayleigh fading channels. However, that model, as shown in this paper, may encounter statistic deficiency. Therefore, an improved model is presented to remove the statistic deficiency. Furthermore, a new simulation model is proposed for Rician fading channels. This Rician fading simulator with finite number of sinusoids plus a zero-mean stochastic sinusoid as the specular (line-of-sight) component is different from all the existing Rician fading simulators, which have non-zero mean deterministic specular component. The statistical properties of the proposed Rayleigh and Rician fading channel models are analyzed in detail, which shows that these statistics either exactly match or quickly converge to the theoretically desired ones. Additionally and importantly, the probability density function of the Rician fading phase is not only independent from time but also uniformly distributed, which is fundamentally different from that of all the existing Rician fading models. The statistical properties of the new simulators are evaluated by numerical results, finding good agreement in all cases

Channel Modeling and Direction-of-Arrival Estimation in Mobile Multiple-Antenna Communication Systems

Antennas that are able to adaptively direct the transmitted (and received) energy are of great interest in future wireless communication systems. The directivity implies reduced transmit power and interference, and also a potential for increased capacity. This thesis treats some modeling and estimation problems in mobile communication systems that employ multiple antennas, primarily at the base stations. With multiple antennas at the receive side, the spatial dimension is added, and processing is performed in both the temporal and spatial domains. The potential benefits are increased range, fading diversity and spatially selective transmission. Specifically, the problems dealt in this thesis are mainly related to the uplink transmission from mobile to the base station. Two main topics are studied, channel modeling and estimation of channel parameters. This thesis first describes the modeling of the reflected power distribution due to the scatterers close to the mobile stations, in terms of the received signal azimuth at the base station with multiple-antenna. As a more realistic channel modeling, a multipath fading deterministic channel model is proposed to generate properly correlated faded waveforms with appropriate power distribution through azimuth spread of received signal. The purpose of the proposed channel model is to model fading received signal waveforms with Laplacian distribution of power through received signal azimuth spread. This thesis is divided into two parts; in the first part multipath fading by local scattering are used to derive a channel model including the spatial dimension for non frequency-selective fading. This means that the mobile is not modeled as a point source but as a cluster of a large number of independent scatterers with small time delay spread to take into account angular spreading of the signal. Properly correlated fading waveforms are obtained by taking into account the angular spread of the scattered signals from a particular distribution of scatterers. By appropriate scaling of the array response vector (ARV) based on non-equal locations for various received signal components as a function of distance from the transmitter, the reflected power from a given scatterer is no longer constant but varies as a function of the distance from the transmitter. Our proposed channel model is able to produce fading signal waveform which agrees with the results of reflected angular power dispersions measured in the field, e.g. Laplacian distribution of power in azimuth. It is also shown that the channel response can be modeled as a complex Gaussian vector. Although the channel will be frequency selective in the case of multipath propagation with considerable time spread, this can be modeled as having more than one cluster of scatterers. By employing Walsh-Hadamard codewo VdLrs)l wideband multipath fading model is achieved. It is shown that the statistical properties of proposed model such as signal waveform's correlation, autocorrelation and crosscorrelation between generated paths, are in good agreement with the theory in space and time domain. The model can be applied to evaluate smart antenna systems and beamforming algorithms in the uplink by generating uncorrelated multipaths Rayleigh fading waveforms with certain spatio-temporal correlation and spatial coordinates relative to base stations to simulate received signals from mobiles and interferers. Bit-error-rate (BER) performance analysis of uniform linear array antenna (ULA) based on correlation - matrix is also presented as an application of our proposed model for multipleantenna evaluations. Our simulated results show 5% improvement than other published related works. One problem when modeling frequency selective fading is that each cluster has to be assigned spatial parameters. Since the joint spatial and temporal characteristics are unknown, non-parametric channel estimation approaches are required in this case in order to estimate the channel parameter, which is the subject of the second part. The second part of the thesis deals with channel parameter estimation of distributed scattering sources. Because of local scattering around the transmitter the signal waveforms appears spatially distributed at the receiver. The characterization of the spatial channel, in particular mean direction of arrival and spatial spread, is of prime interest for system optimization and performance prediction. Low-complexity spectral-based estimators are used for the estimation of direction and spatial spread of the distributed source by employing the proposed channel model for simulation. Estimated parameters from recent measurements ([PMFOO]) are compared with estimated parameters from model generated waveforms as well as theoretical distribution of received signal's angular spread. Good agreement between them is observed which shows the correctness of our proposed channel model for simulating spatio-temporally correlated received signal at an antenna array. The estimated parameter error improved by 5% over the other published related works

Efficient sum-of-sinusoids-based simulation of mobile fading channels with asymmetric Doppler power spectra,” The

Abstract-In this paper, we deal with the problem of designing efficient sum-of-sinusoids (SOS) based simulators for frequency non-selective mobile fading channels under non-isotropic scattering conditions. To cope with this problem, we propose a new parameter computation method that can be applied on any given asymmetrical Doppler power spectrum (DPS). With the aim to reduce the computational costs associated with the simulation of high-quality channel waveforms, we also present an efficient simulation approach that combines the proposed parameter computation method with the principle of set partitioning. By considering a reference model for a fading channel with asymmetrical DPS, it is shown that the resulting SOSbased channel simulator satisfactorily emulates the channel's autocorrelation function (ACF). Owing to its characteristics, the proposed channel simulation procedure proves to be a helpful tool for the test and performance analysis of modern wireless communication systems under non-isotropic scattering scenarios

Study and Simulation of Quasi and Rotated Quasi Space Time Block Codes in MIMO systems using Dent Channel model

Multiple Input Multiple Output (MIMO) has become one of the most exciting fields in modern engineering. It is mainly used to increase data rate and capacity of wireless communication system. In this paper, we exploit the space and time diversity to decode the quasi and rotated quasi space time block codes (QOSTBC) based on dent channel model. For Doppler shifting and Rayleigh distribution we make use of dent channel model. This provides fast decoding and gives better performance of communication system.BER analysis is presented in terms of diversity and code rate. KEYWORDS: MIMO, Quasi Orthogonal Space-Time Block codes (QOSTBC), rotated QOSTBC, Maximum Likelihood (ML) decoding

Development of a MATLAB Toolbox for Mobile Radio Channel Simulators

A profound knowledge of mobile radio channels is required for the development, evaluation, and also assessment at practical conditions of present and future mobile radio communication systems. The modelling, analysis, and simulation of mobile radio channels are important sub area since the initiation of mobile communications. In addition to that knowledge of channel behaviour in mobile radio communication is extensively recommended for the study of transmitter/receiver performances. Our intention in this master's thesis is to develop various kinds of mobile fading channel simulators using MATLAB and embed them into MATLB software as a toolbox. Implemented channel simulators were combined into a user-friendly Matlab toolbox from which users can easily select well-known channel models to test and to study the performance of mobile communication systems. The help file was developed based on HTML. It gives better support for the new users to work on the developed channel simulators, run the test procedures as well as parameter computation. The help file consistent with other supplementary programs like computation of PDF and CDF for different distributions, Rice simulation model, extended Suzuki process type I and II simulator etc. In addition to that each program consists with guidelines embedded with the source code. The help file web interfaces are listed in Appendix- 1.The toolbox can be integrated into the new release of Matlab software. The toolbox contains channel simulators for simulating non-stationary land mobile satellite channel, spatial shadowing processes, MIMO channels, multiple uncorrelated Rayleigh fading channels, mobile to mobile channel, frequency hopping channels etc. We developed set of test procedures, such as the autocorrelation function ACF, average duration of fades ADF, the probability density function PDF, and the level-crossing rate LCR etc., in order to test and to confirm the correctness of the implemented channel simulators. Proposed new algorithms to compute the model parameters of the channel simulators were also implemented in the toolbox to enable the parameterization of the channel simulators under specific propagation conditions. Finally, “how can a channel simulator be tested?” have been address in the thesis as a research question. It was based on the comparison of simulation results with the measured model or the reference model under different scenarios. In addition to that selection of the simulation time duration, sampling rate and size of the samples were considered. Developed test procedures were helped to assess the implemented channel simulators

CDMA2000 Downlink Performance Analysis Based on Deterministic Ray-Tracing Channel Model

This paper presents frame error rate (FER) properties of downlink in CDMA2000 system with the movement of the mobile terminal in high-rise urban environment. The site-specific channel model based on ray-tracing technique is chosen for this analysis with the established cells and sectors for the current IS-95 service. The tendency of FER according to the position of the mobile terminal is analyzed. From this analysis, we can infer the possibility of using the established IS-95 cell plannings for the CDMA2000 service