4,791 research outputs found
Outage rates and outage durations of opportunistic relaying systems
Opportunistic relaying is a simple yet efficient cooperation scheme that
achieves full diversity and preserves the spectral efficiency among the
spatially distributed stations. However, the stations' mobility causes temporal
correlation of the system's capacity outage events, which gives rise to its
important second-order outage statistical parameters, such as the average
outage rate (AOR) and the average outage duration (AOD). This letter presents
exact analytical expressions for the AOR and the AOD of an opportunistic
relaying system, which employs a mobile source and a mobile destination
(without a direct path), and an arbitrary number of (fixed-gain
amplify-and-forward or decode-and-forward) mobile relays in Rayleigh fading
environment
On the Second Order Statistics of the Multihop Rayleigh Fading Channel
Second order statistics provides a dynamic representation of a fading channel
and plays an important role in the evaluation and design of the wireless
communication systems. In this paper, we present a novel analytical framework
for the evaluation of important second order statistical parameters, as the
level crossing rate (LCR) and the average fade duration (AFD) of the
amplify-and-forward multihop Rayleigh fading channel. More specifically,
motivated by the fact that this channel is a cascaded one and can be modeled as
the product of N fading amplitudes, we derive novel analytical expressions for
the average LCR and the AFD of the product of N Rayleigh fading envelopes (or
of the recently so-called N*Rayleigh channel). Furthermore, we derive simple
and efficient closed-form approximations to the aforementioned parameters,
using the multivariate Laplace approximation theorem. It is shown that our
general results reduce to the corresponding ones of the specific dual-hop case,
previously published. Numerical and computer simulation examples verify the
accuracy of the presented mathematical analysis and show the tightness of the
proposed approximations
Level Crossing Rate and Average Fade Duration of the Multihop Rayleigh Fading Channel
We present a novel analytical framework for the evaluation of important
second order statistical parameters, as the level crossing rate (LCR) and the
average fade duration (AFD) of the amplify-and-forward multihop Rayleigh fading
channel. More specifically, motivated by the fact that this channel is a
cascaded one, which can be modelled as the product of N fading amplitudes, we
derive novel analytical expressions for the average LCR and AFD of the product
of N Rayleigh fading envelopes, or of the recently so-called N*Rayleigh
channel. Furthermore, we derive simple and efficient closed-form approximations
to the aforementioned parameters, using the multivariate Laplace approximation
theorem. It is shown that our general results reduce to the specific dual-hop
case, previously published. Numerical and computer simulation examples verify
the accuracy of the presented mathematical analysis and show the tightness of
the proposed approximations
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