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

Simulation of WLAN Based V2X Signal Models Using Deterministic Channel

Vehicle to everything (V2X) communication is one of the important topics in the telecommunication field aiming to provide a great improvement in the transport sector by increasing safety and comfort while driving as well as reducing traffic congestion and as a result there are a lot of researches , developments and investments made in this field. This thesis presents the use of Unity 3D game engine program for the creation of a deterministic channel model through which we can analyse and study the performance of the WLAN based signal models that are used in the vehicle to everything (V2X) technology.AN open source V2X simulator was used for the process of channel creation and performance assessment making use of its real time stochastic measurements .Two different methods were used to assess the performance of both the IEEE 802.11p and 802.11bd signal models with different calculations but eventually the latter proved to be the superior since it is considered the most advanced and latest version of the IEEE 802.11 family

Estudo do comportamento de canal em redes 5G: uma análise preditiva

A paramether that begins to be particularly important on the dimensionament of the 5G networks is the communication channel state, mainly considering the new frequencies used, the growing number of connected devices and the necessity of allocate resources efficiently. To dimension the channel effects, the Base Station (BS) receives from the User Equipment (UE) a measurement of the channel quality, called Channel Quality Information/Indicator (CQI), from wich makes the scheduling of the resources to better attend the users. The study developed here wants to generate a reliable data base of a CQI flow along a transmission into a mobile network Long Term Evolution Advanced (LTEA) with some parameters of the Release 15 of the Technical Specification (TS) from 3rd Generation Partnership Project (3GPP) of 5G using Matlab. After this, it is purposed the aplication of a temporal neural network to predict the CQI along a transmission. Lastly, evaluates the reability of the network, comparing the predicted values by the system and the real ones.Trabalho de Conclusão de Curso (Graduação)Um parâmetro que passa a ser particularmente importante no dimensionamento das redes 5G é o estado do canal de comunicação, principalmente ao considerar as novas frequências usadas, o número crescente de dispositivos conectados e a necessidade de alocar recursos de forma eficiente. Para dimensionar os efeitos do canal, a Base Station (BS) recebe do User Equipment (UE) uma medição da qualidade do canal, chamada Channel Quality Information/Indicator (CQI), a partir da qual faz o escalonamento dos recursos para melhor atender os usuários. O estudo aqui desenvolvido visa gerar uma base de dados confiável de um fluxo de CQI ao longo de uma transmissão em uma rede móvel Long Term Evolution Advanced (LTE-A) com alguns parâmetros da Release 15 das Technical Specification (TS) do 3rd Generation Partnership Project (3GPP) para o 5G usando o Matlab. Após isso, propõe-se a aplicação de uma rede neural temporal para prever o CQI ao longo de uma transmissão. Por fim, avalia-se a confiabilidade da rede, comparando os valores preditos pelo sistema e os reais

Estudo e modelamento de um canal fading sob efeito de sinais multipercursos utilizando distribuição de rayleigh e filtros FIR

Orientador: Prof. Horácio Tertuliano Santos, Ph.DDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa : Curitiba, 07/08/2018Inclui referências: p.97-99Área de concentração: TelecomunicaçõesResumo: O presente trabalho visa caracterizar um dos efeitos estocásticos que mais afetam as redes de telecomunicações, principalmente as de comunicações móveis: o fenômeno fading ou desvanecimento de canal. Para seu completo entendimento faz-se necessário o conhecimento prévio do comportamento físico das antenas transmissoras e receptoras, fixas ou móveis, bem como toda a sistemática de transmissão no espaço livre com a devida caracterização física das ondas eletromagnéticas e seu comportamento como atenuação, reflexão, difração e espalhamento. Para estabelecer estas bases o tratamento matemático e físico se torna imprescindível bem como o rigor na descrição da geometria dos enlaces. Quanto às comunicações móveis o efeito Doppler é um elemento a ser considerado como dos mais relevantes no processo causador do fenômeno fading juntamente com os efeitos de trajetos multipercursos, principalmente em ambientes urbanos com alta densidade de possíveis obstáculos. A simulação para o fenômeno fading é realizada fazendo-se passar um sinal através de um filtro FIR simulando um canal de comunicação e algoritmos implementados no MATLAB, onde se mostram os comportamentos dos sinais multipercursos e o efeito Doppler. Será utilizado o modelo de Rayleigh que é a distribuição estatística que melhor representa o fenômeno fading em situações onde há ocorrência de multipercursos ou intensos níveis de reflexões e espalhamentos causando rápidas e profundas variações no nível do sinal chegando ao receptor. O canal será simulado com o uso de filtro FIR digitalmente implementado. A contribuição do estudo e das simulações é a de ser uma ferramenta para projetistas mitigar os efeitos do fenômeno fading em estudos antes da implantação do projeto de links ou redes ou em sua expansão e diminuir a taxa de erros de transmissão BER (bit error rate) devido a ruídos no canal de comunicação. Palavras-chave: Fading, modelo fading de Rayleigh, Efeito Doppler, Modelo multipercurso, filtros FIR, BER.Abstract: The present work intends to characterize one of the stochastic effects that most affects telecommunications networks, mostly mobile communications, the fading phenomenon. For complete understanding, it is necessary a previous knowledge about the physical behavior of transmitting and receiving antennas, base stations or mobiles, as well as the entire transmission systematic in free space with the proper physical characterization of the electromagnetic waves and its behavior as attenuation, reflection, diffraction and spreading. To establish these bases, mathematical and physical treatment becomes essential as well as the accuracy in the description of the links geometry. In relation to the mobile communication, the Doppler effect is an element to be considered as one of the most relevant at the prompter process of fading phenomenon besides multipaths effect, mainly at urban environments with high density of possible obstacles. The simulation for the fading phenomenon is performed by passing a signal through a FIR filter simulating a communication channel and implemented algorithms at MATLAB, where the multipath signals behavior and Doppler effect are showed. The Rayleigh model is a statistical distribution that better describe the fading phenomenon in situations where occurs multipath or intense reflections or scattering levels causing fast and deeply variations at the signal level arriving to the receiver. The communication channel will be simulated using a FIR filter digitally implemented. The study and simulations contribution are about been a tool for designers to mitigate the fading phenomenon effects in studies before network projects implementation or on its expansion reducing the errors rate BER (bit error rate) transmission due to noises at the communication channel. Key-words: Fading, channel fading, Rayleigh's fading channel, Doppler effect, Multipath model, FIR filters, BER

Design of Mobile Radio Channel Simulators Using the Iterative Nonlinear Least Square Approximation Method with Applications in Vehicle-to-X Communications

Doktorgradsavhandling i informasjons- og kommunikasjonsteknologi, Universitetet i Agder, 2015Vehicle-to-X (V2X) communication systems are expected to provide tremendous benefits associated with the safety and traffic efficiency on roads. The successful deployment of emerging technologies like V2X requires channel models accurately representing fading statistics in environments where those technologies are used. The accuracy is, of course, a major concern when adapting or developing a suitable channel model for test and evaluation purposes. However, it is also important to take into account the simplicity of a channel model, which is crucial for efficient numerical computations and computer simulations. Reconciling simplicity and accuracy is a rather complex task to accomplish, which requires sophisticated parameter computation methods. To the best of our knowledge, only a limited number of investigations address the channel modelling and parametrization problems for vehicular propagation scenarios in the literature. In order to fill this gap, we concentrate on the development of new sophisticated channel modelling approaches and efficient parameter computation methods for the design of V2X communication systems in this dissertation. In general, there are two main applications of channel models: (1) for the design and test of wireless communication systems and (2) for the optimization of existing communication systems. For the design and test purposes, more general statistical models such as Rice and Rayleigh channel models are preferred. Those channel models provide a fundamental insight into propagation phenomena and at the same time they greatly simplify the theoretical and numerical computations to assess the performance of wireless communication systems. For the optimization purposes, however, measurement-based channel models are commonly used. The main advantage of such channel models is that they always accurately reflect the physical reality. In this dissertation, we will focus on the channel models designed for both of those application purposes. A significant part of this dissertation will be devoted to the thorough analysis and design of Rayleigh and Rice fading channel models. We investigate the correlation properties of those channels assuming asymmetrical shapes of Doppler power spectral densities (PSDs). In fact, this is what we often observe in real-world propagation scenarios. In this regard, we will present an analytical expression for the autocorrelation function (ACF) of Rice processes that captures such realistic scenarios. Another important contribution to this topic is the novel iterative nonlinear least square approximation method for the design of Rice and Rayleigh channel simulators based on sum-of-sinusoids (SOS), as well as sum-of-cisoids (SOC) approaches. The idea behind the proposed method is very simple. The parameters of the simulation model are extracted from the reference model, such as the stochastic Rice and Rayleigh channel models, by fitting the statistical properties of interest, e.g. the ACF and the probability density function (PDF). We show that the proposed method outperforms several other methods in designing channel simulators with desired distribution and correlation properties. We also show that the proposed method provides a subtle balance between channel model’s simplicity and accuracy in designing Rayleigh and Rice channel simulators. The parametrization is a process of determining the key parameters specifying the channel model. This process has a great influence on the reliability of the developed channel model. It is therefore highly desirable if those parameters are extracted from measurements. In fact, this idea constitutes the fundamental concept behind measurement-based channel modelling approach. The measurement-based models are important in the sense that they can be used for the optimizations of the wireless communication system. Hence, the problem of computing the channel model parameters from the measurements is of special interest. In this regard, we propose iterative nonlinear least square approximation method for the design of measurementbased channel simulators. Through detailed investigations and comparative studies, we demonstrate that the proposed method is highly flexible and outperforms several other conventional methods in terms of reproducing the correlation characteristics obtained from several measurements. In addition, we introduce a new approach for the design of channel models for V2X communications in tunnel environments, where the number of scatterers contributing to the total received power is relatively small

Network Coding for Multihop Wireless Networks: Joint Random Linear Network Coding and Forward Error Correction with Interleaving for Multihop Wireless Networks

Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment.Indonesian Government and the University of Bradfor