Fading distribution

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

Multipath Phenomena in Cellular Networks

Abstract: Introduction to the Multipath Phenomena - Statistical Description of the Multipath Propagation Channels. Narrowband Signal Fading in the Space and Time Domains. Wideband Signal Fading in the Time and Frequency Domains. Fading Phenomena - Path Loss Phenomenon in Various Land Environments. Distribution of Angle-of-Arrival and Time Delay Resulting by Multipath Phenomena. Signal Power Fading in Angle and Time Domains. Spectral Properties of Multipath Phenomena. Characterization and Consequences of Multipath Radio Channels - Prediction of Multipath Characteristics for Communications and Positioning. System Aspects of Multipath.

Capacity per unit energy of fading channels with a peak constraint

Abstract: A discrete-time single-user scalar channel with temporally correlated Rayleigh fading is analyzed. There is no side information at the transmitter or the receiver. A simple expression is given for the capacity per unit energy, in the presence of a peak constraint. The simple formula of Verdu/spl acute/ for capacity per unit cost is adapted to a channel with memory, and is used in the proof. In addition to bounding the capacity of a channel with correlated fading, the result gives some insight into the relationship between the correlation in the fading process and the channel capacity. The results are extended to a channel with side information, showing that the capacity per unit energy is one nat per joule, independently of the peak power constraint. A continuous-time version of the model is also considered. The capacity per unit energy subject to a peak constraint (but no bandwidth constraint) is given by an expression similar to that for discrete time, and is evaluated for Gauss-Markov and Clarke fading channels.

Capacity of the Multiple Spot Beam Satellite Channel With Rician Fading

Abstract: In this correspondence, the uplink of a multibeam satellite system with Rician fading is analyzed under the framework of Wyner's Gaussian cellular multiple access channel. In this framework the received signal at a given multibeam antenna is the sum of signals transmitted by users within that beam's cell area plus a factor 0 les alpha les 1 times the sum of the signals transmitted by users from adjacent cells plus ambient Gaussian noise. Both one-dimensional (1-D) linear, and 2-D hexagonal cellular arrangements are considered. In addition, we consider a modified version of the 1-D linear arrangement whereby users from cells further than adjacent cells contribute to intercell interference. It is assumed that the distance between the antenna elements is small compared to the distance between a user and the satellite. Thus when fading is present, a particular user's fading coefficient is the same at each multibeam antenna. This is the fundamental difference between the multibeam satellite fading channel and the terrestrial cellular fading channel, in which each user experiences independent fading at each base station. Using a Haar measure approximation we derive closed form approximations for the capacity of the satellite fading channel for the scenarios when optimal joint decoding and linear minimum mean square error filtering is employed at the ground station. These approximations are shown to be in close agreement to Monte Carlo simulation results for large dimensional systems. It is shown that fading causes a loss in capacity compared to the nonfading channel. Furthermore, at high signal-to-noise ratio (SNR) this loss is independent of the intercell interference and topology of the system, but is dependent on the distribution of the fading coefficients and the number of users per beam.

Optimal Power-Delay Tradeoffs in Fading Channels—Small-Delay Asymptotics

Abstract: When transmitting stochastically arriving data over fading channels, there is an inherent tradeoff between the required average transmission power and the average queueing delay experienced by the data. This tradeoff can be exploited by appropriately scheduling the transmission of data over time. In this paper, we study the behavior of the optimal power-delay tradeoff for a single user in the regime of asymptotically small delays. In this regime, we first lower bound how much average power is required as a function of the average queueing delay. We show that the rate at which this bound increases as the delay becomes asymptotically small depends on the behavior of the fading distribution near zero, as well as the arrival statistics. We lower bound this rate for two different classes of fading distributions: one class that requires infinite power to minimize the queueing delay and one class that requires only finite power. We then show that for both classes, the bounds can essentially be achieved by a sequence of simple “channel threshold” policies, which only transmit when the channel gain is greater than a given threshold. We also consider several other transmission scheduling policies and characterize their convergence behavior in the small-delay regime.