Fading distribution

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

On the capacity of cellular DS/CDMA systems under slow Rician/Rayleigh-fading channels

Abstract: Power control is essential for code-division multiple-access (CDMA) cellular systems to overcome the near-far problem. Fast power control tracks multipath fading perfectly which increases the intercell interference and thus reduces the capacity. If there is a line of sight (LOS) component between the mobile and the base station with which it is communicating, the fading will be of Rician type and less deep fades will be encountered which reduces the intercell interference. In this paper, we investigate the system capacity assuming the fading between a mobile and the base station with which it is communicating to be Rician with a Rician factor K with the fading between the same mobile and other base stations to be Rayleigh. We show a large increase in the capacity even for small Rician factors. A Rician fading is usually encountered when the mobile is close to the base station and thus the path-loss exponent can be less than four. Thus, we investigate the effect of changing the path-loss exponent value on the system capacity. Finally, we reduce the intercell interference by imposing a limit on the maximum increase in power to compensate for multipath fading and show how can this increase the capacity by more than 100%.

Symbol-error rate of selection combining over two-wave with diffuse power fading

Abstract: Symbol-error rate expressions of selection combining over the two-wave with diffused power (TWDP) fading channel are derived using the moment-generating function approach. The TWDP fading model is characterized by two specular waves in the presence of other diffused waves and has both the Rayleigh and Rician fading channels as special cases. The TWDP fading model is applicable to both the narrow-band and wide-band operations and when directional antennas are used. The derived theoretical expressions are validated by simulation results.

The Effect of Fading on Communication Circuits Subject to Interference

Abstract: The statistical performance of radio communication circuits in the presence of interference is analyzed for the cases where either the desired or undesired signal or both are subject to Rayleigh fading over the propagation path. The significant parameter considered is the ratio of mean signal power to mean interference power needed at the receiver for satisfactory performance. When satisfactory performance is required a high percentage of the time the signal power must be greatly increased over the nonfading case, e.g., 99.9 per cent satisfactory operation requires 30 db more signal power in the presence of signal fading whether or not the interference is fading. The improvement which dual diversity reception offers is discussed for each case. For 99.9 per cent satisfactory operation a practical dual diversity system offers a 14 db improvement over nondiversity for fading signal and fading interference.

Fading wiretap channel with no CSI anywhere

Abstract: We consider the fast Rayleigh fading wiretap channel, over which a legitimate transmitter wishes to have secure communication with a legitimate receiver in the presence of an eavesdropper. We consider an average power constraint on the input, and assume that no channel state information (CSI) is available to any user. We show that the input distribution that achieves the secrecy capacity for this wiretap channel is discrete with a finite number of mass points.

Analysis of capacity and probability of outage for free-space optical channels with fading due to pointing and tracking error

Abstract: Free-space laser communications systems experience fading due to quasi-static pointing error and tracking error that impairs communications performance. Under a block fading model we show that using forward error correcting codes and interleaving - a simple non-mechanical data processing technique - much of the harmful effect of tracking error on communications performance can be removed. Using the concepts of fading capacity and outage capacity, we provide analytical tools that quantify the effects of fading on communications performance with and without interleaving. A link budget based on this analysis includes three loss terms due to pointing and tracking error: 1) static loss, which is primarily a function of pointing error; 2) capacity loss, which is the power difference between fading capacity and fade-free capacity; and 3) finite interleaver loss, which is the power difference between the probability of outage curve and fading capacity. Assuming pulse-position modulation and a Poisson channel, we derive closed-form solutions for the probability of outage of interleaved systems using a Gaussian beam with circularly symmetric Gaussian tracking error.