Rician fading or Ricean fading is a stochastic model for radio propagation anomaly caused by partial cancellation of a radio signal by itself — the signal arrives at the receiver by several different paths (hence exhibiting multipath interference), and at least one of the paths is changing (lengthening or shortening). Rician fading occurs when one of the paths, typically a line of sight signal or some strong reflection signals, is much stronger than the others. In Rician fading, the amplitude gain is characterized by a Rician distribution.
Rayleigh fading is sometimes considered a special case of Rician fading for when there is no line of sight signal. In such a case, the Rician distribution, which describes the amplitude gain in Rician fading, reduces to a Rayleigh distribution. Rician fading itself is a special case of two-wave with diffuse power (TWDP) fading.
A Rician fading channel can be described by two parameters. The first one, , is the ratio between the power in the direct path and the power in the other, scattered, paths:
The second one, , is the total power from both paths, and acts as a scaling factor to the distribution:
The received signal amplitude (not the received signal power) is then Rice distributed with the following parameters:
The resulting Probability density function is:
where is the 0th order modified Bessel function of the first kind.
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.
This course complements the theoretical knowledge learned in PDC with more advanced topics such as OFDM, MIMO, fading channels, and GPS positioning. This knowledge is put into practice with hands-on e
The students will learn about the basic principles of wireless communication systems, including transmission and modulation schemes as well as the basic components and algorithms of a wireless receive
En probabilités et en statistiques, la loi de Rayleigh, est une loi de probabilité à densité. Elle apparaît comme la norme d'un vecteur gaussien bi-dimensionnel dont les coordonnées sont indépendantes, centrées et de même variance. Cette loi de probabilité est baptisée d'après Lord Rayleigh. Typiquement, la distance D à laquelle une particule se trouve de son point de départ, après avoir effectué n pas d'une marche aléatoire symétrique dans le plan, suit approximativement une loi de Rayleigh de paramètre .
In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics. Diversity is mainly used in radio communication and is a common technique for combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience fades and interference at different, random times, i.e, they are at least partly independent.
Rayleigh fading is a statistical model for the effect of a propagation environment on a radio signal, such as that used by wireless devices. Rayleigh fading models assume that the magnitude of a signal that has passed through such a transmission medium (also called a communication channel) will vary randomly, or fade, according to a Rayleigh distribution — the radial component of the sum of two uncorrelated Gaussian random variables.
Couvre les canaux qui s'estompent dans la communication sans fil, en discutant des modèles, des performances, de la diversité et des effets d'atténuation.
Explore le taux réalisable, la capacité, l'efficacité énergétique, l'efficacité spectrale et les probabilités d'erreur dans les systèmes de communication.
Information theory has long pointed to the promise of physical layer cooperation in boosting the spectral efficiency of wireless networks. Yet, the optimum relaying strategy to achieve the network capacity has till date remained elusive. Recently however, ...
EPFL2015
Wireless channels are commonly affected by short-term fading and long-term fading (shadowing). The shadowing effects must be taken into account also when mobility is present in the wireless scenario. Using a composite fading model, the total channel capaci ...
Hindawi Publishing Corporation2015
A central theme of this thesis is using echoes to achieve useful, interesting, and sometimes surprising results. One should have no doubts about the echoes' constructive potential; it is, after all, demonstrated masterfully by Nature. Just think about the ...