Fading distribution

About: Fading distribution is a research topic. Over the lifetime, 5732 publications have been published within this topic receiving 114193 citations.

GPS signal fading model for urban centres

Abstract: The use of GPS receivers in wireless telephones has been proposed as a means of automatically identifying the position of wireless 911 callers. GPS simulators are an efficient means of testing the accuracy of such technology but require a channel model for GPS satellite signals. This paper presents a methodology of measuring and modeling the fading distribution of GPS satellite signals received in outdoor urban centers. GPS fading data, as collected in the downtown areas of Calgary and Vancouver, Canada, are used to generate fade histograms as a function satellite elevation angle. These histograms are found to be sufficiently similar between the two cities and, therefore, lead to the conclusion that a generic fade distribution for urban centers is reasonable. Parameters for the Urban ThreeState Fade Model are estimated from the empirical fading data collected in each city. Correlation between the model parameters derived for each city is significant and also suggests that a generic model may be derived. The parameters from the two cites are averaged to produce a generic Urban ThreeState Fade Model which adequately represents the fade histograms of each city. These averaged parameters generally agree with parameters derived from data collected in Tokyo, Japan.

Bivariate generalised gamma distribution with arbitrary fading parameters

Abstract: The three-parameter generalised gamma distribution is a versatile fading model that generalises or accurately approximates many of the commonly used distributions for multipath, shadow, and composite fading. It is difficult to evaluate the performance(s) of closely spaced dual-diversity receivers operating in such a channel because an analytical expression is not yet available for the bivariate correlated generalised gamma distribution. This report studies the bivariate generalised gamma distribution with arbitrary parameters. Expressions for the joint distribution and joint central moments are derived, and are used to obtain the outage probability for a dual-branch selection combining receiver over a correlated generalised gamma fading channel.

Performance of MC-CDMA systems in non-independent Rayleigh fading

Abstract: In this paper, the average bit error probability of an uplink multi-carrier code division multiple access (MC-CDMA) system using maximal-ratio combiner (MRC) is derived for a frequency-selective slow fading channel. In contrast to a conventional multicarrier channel model in which the subcarriers experience independent subchannels, the subcarriers in MC-CDMA system undergo the correlated fading channel in a general tapped-delay line (TDL) model with variable channel parameters. Numerical results are shown based on the derived result, to show that conventional multicarrier channels tend to overemphasize the performance of an MC-CDMA system.

Spectrum Sensing and Throughput Trade-off in Cognitive Radio under Outage Constraints over Nakagami Fading

Abstract: The spectrum sensing duration and the secondary user's achievable throughput trade-off is optimized under outage constraints in a cooperative cognitive radio network over Nakagami fading conditions. The optimum trade-off depends not only on the maximum outage probability allowed by the primary user and the number of cognitive users involved in the sensing but also on the fading operational conditions of the cognitive radio. The parameters of the Nakagami fading distribution can be adjusted to fit different fading environments. The fading parameter (also called shape parameter) of the Nakagami distribution affects the optimum sensing time, which increases when the fading conditions are worse than Rayleigh fading. For the energy detector, the expression for the probability of false alarm is obtained in terms of a new threshold, which is derived considering an outage constraint on the channel-dependent probability of detection. Then, the optimization problem is formulated. Simulation results quantify the effects of different fading parameters on the optimum spectrum sensing duration.

Capacity for Spectrum Sharing Cognitive Radios with MRC Diversity at the Secondary Receiver under Asymmetric Fading

Abstract: In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio Combining (MRC) diversity at the secondary receiver under asymmetric fading, where the channel from secondary transmitter to primary receiver suffer Nakagami-m fading while the one from secondary transmitter to its receiver follows Rayleigh Multipath fading. Our mathematical analysis and numerical results show that with MRC combining diversity at the secondary receiver, more capacity is achieved. In addition, when the SU$_{tx}$-PU$_{rx}$ channel has less severe fading which strongly affects the capacity of CR channel, utilizing MRC combining technique for CR system could reduce the effects.