Performance of orthogonal frequency division multiplexing system in terrestrial TV channels-a statistical analysis (original) (raw)
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Theory of multipath shape factors for small-scale fading wireless channels
IEEE Transactions on Antennas and Propagation, 2000
This paper presents a new theory of multipath shape factors that greatly simplifies the description of small-scale fading statistics of a wireless receiver. A method is presented for reducing a multipath channel with arbitrary spatial complexity to three shape factors that have simple intuitive geometrical interpretations. Furthermore, these shape factors are shown to describe the statistics of received signal fluctuations in a fading multipath channel. Analytical expressions for level-crossing rate, average fade duration, envelope autocovariance, and coherence distance are all derived using the new shape factor theory and then applied to several classical examples for comparison. Index Terms-Angle of arrival, diversity, fading channels, mobile communications, multipath channels, propagation, scattering. I. INTRODUCTION T HE motion in space of a wireless receiver operating in a multipath channel results in a communications link that experiences small-scale fading. The term small-scale fading describes the rapid fluctuations of received power level due to small subwavelength changes in receiver position [1]. This effect is due to the constructive and destructive interference of the numerous multipath waves that impinge upon a wireless receiver [2]. The resulting signal strength fluctuations affect, in some way, nearly every aspect of receiver design: dynamic range, equalization, diversity, modulation scheme, and channel and error-correction coding. Due to its random unpredictable nature, small-scale fading is always studied as a stochastic process. Numerous researchers have measured and analyzed the first-order statistics of these processes, which mostly involves the characterization of smallscale fading with a probability density function (PDF) [3]-[5]. The autocorrelation statistics of fading processes or secondorder statistics have also been studied [6], [7]. Second-order statistics include measures of a process such as power spectral density (PSD), level-crossing rate, and average fade duration. Second-order statistics are heavily dependent on the angles-of-arrival of received multipath. Traditionally, most second-order statistics have been studied using an omnidirectional azimuthal propagation model [2]. That is, multipath waves are assumed to arrive at the receiver with equal power
STUDY OF VARIOUS MULTIPATH CHANNELS& SMALL-SCALE FADING& ITS PERFORMAMCE IN WIRELESS COMMUNICATION
In this Research, we exhibit a time-frequency point of view of wireless communications after some time-varying multipath channels. Our discourse is principal with regards to code-division multiple access (CDMA) systems in light of their outstanding capacity to battle multipath blurring. Beginning with a time-frequency portrayal of the mobile wireless channel, we land at a sanctioned nite-dimensional time-frequency portrayal of the channel that will fill in as the foundation of our treatment. The accepted time-frequency-based channel portrayal demonstrates that spread-range signalling after
Radio Propagation in Terrestrial Broadcasting Television Systems: A Comprehensive Survey
IEEE Access, 2021
During the last two decades, terrestrial TV broadcasting has evolved from analog to digital technology, permitting a better spectrum efficiency, being more resistant to noise and interference as well as improving signal quality. High Definition TeleVison (HDTV) has been introduced to enhance the viewer's experience. HDTV and Ultra High Definition TeleVision bring the challenge of having a quasi-error free performance at a bit error rate as low as 10 −12 ; i.e. less than one uncorrectable error during one hour's continuous transmission of 5 Mbps data stream. Such low error rates require robust standards, careful network planning and optimized service operation. Propagation phenomena have a direct (and possibly critical) impact on those three pillars. This paper fills the current gap of a thorough survey on propagation methods and models for broadcasting. We contribute to this field with a description and analysis of propagation phenomena concerning different aspects of the broadcast network planning, broadcast standard evaluation, and broadcast service operation. The paper provides also a technical perspective of state-of-the-art TV broadcast standards and discusses the relevancy of propagation studies with future and development and regulation challenges. INDEX TERMS Broadcasting, digital terrestrial television, radio propagation. FIGURE 2. Propagation mechanisms affecting DTTB systems.
Influence of multipath radio propagation on wideband channel transmission
International Multi-Conference on Systems, Sygnals & Devices, 2012
The mobile radio propagation environment clearly places fundamental limitations on the performance of radio communication systems. Signals arrive at a receiver via a scattering mechanism and the existence of multiple propagation paths (multipath) with different time delays, attenuations and phases gives rise to highly complex time varying transmission channel. In order of systems engineers to determine optimum methods of mitigating the impairments caused by multipath propagation, it is essential that the transmission channel be properly characterized.
Proceedings of the 38th IEEE Conference on Decision and Control (Cat. No.99CH36304), 1999
For long-term propagation the signal envelop fluctuations This paper discusses the use of stochastic differential equations to model signal envelope variations over areas, which are subject to short-term fading effects. The short-term fading effects are modeled using Ornstein-Uhlenbeck processes and they are derived from first principles, using the scattering assumption of electromagnetic waves. This gives rise to signal envelope variations which follow a mean-reverting squareroot process, which is elastically pulled towards a long-term mean which characterizes the propagation environment. The derived signal envelope distributions include generalizations of Rayleigh, Ricean Nakagami etc. distributions to their non-stationary analogs and thus generalizing channel models to include time variations. From these computations the second order statistics of the received signal are obtained.
Study of Modulation Schemes over a Multipath Fading Channels
IJMTST, 2021
Communications systems concerted over wireless channels depend on the environment. Communications system can be more reliable and efficient by properly analyzing wireless channels. Today's most important features are a high data rate and reliable performance to exploiting viable networks during this new information age. The channel is not time-invariant in wireless communication, so the received signal exhibits amplitude, phase, and angle variations due to multipath fading. Increasing data rates and reducing bandwidth make Orthogonal Frequency Division Multiplexing (OFDM) an important component of wireless communication systems. The OFDM technique uses many carriers very efficiently. With this scheme, interference is robustly reduced, and fading scenarios are easily accommodated. Analyzing digital modulation schemes requires evaluating link performance with fading channels. The paper compares channel performance over varying fading environments using a variety of modulation schemes. We study the BER and SNR properties of the AWGN, Rician fading and Rayleigh fading channels modulated with BPSK, QPSK, and M-ary QAM.
Performance Analysis of OFDM in Combating Multipath Fading
Mobile Communication system has been on high rampage for high data transmission over wireless medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years to deal with this problems because of its ability to elegantly cope with multipath interference. This paper investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping. Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM allows data transmission with minimal error over fading channel than a Single Carrier.
2007
FIGURE A. 1.4: MULTIPATH 5 FIGURE A. 1.5: MULTIPATH POWER DELAY PROFILE 6 FIGURE A. 1.6: TAPPED DELAY LINE MODEL 7 FIGURE A. 2.1: PARAMETERS OF THE COST-231 WI MODEL [MOLISCH2005] 10 FIGURE A. 2.2: STREET ORIENTATION ANGLE [CICHON] 11 FIGURE A. 2.5. 1: GENERIC STRUCTURE OF SUI CHANNEL MODELS 15