Volume 13, Issue 2 (2013)                   MJEE 2013, 13(2): 51-56 | Back to browse issues page

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Rezaeifar S, Hodtani G A. On Ergodic Capacity and Outage Probability for Secondary Users in Point-to-Point and Multiple Access Channels. MJEE. 13 (2) :51-56
URL: http://mjee.modares.ac.ir/article-17-1675-en.html
1- , M.Sc. Student, Ferdowsi University of Mashhad, Mashhad
2- , Associate Professor, Ferdowsi University of Mashhad
Abstract:   (3669 Views)
Nowadays, the spectrum is becoming more
and more scarce because of not only the demand increase
for wireless services and applications but also inflexible and
rigid spectrum allocation policies. A promising solution to
overcome this challenge is to exploit spectrum holes for
secondary users in cognitive radio. Taking advantage of
cognitive radio and dynamic spectrum access improves the
efficiency of spectrum utilization as it allows secondary
users to exploit the available frequency bandwidth. In
an opportunistic spectrum access scenario, the secondary
users can only utilize the frequency bandwidth when the
primary user is inactive. In this paper, we assume that
secondary users exploit the available frequency bandwidth
using opportunistic spectrum access approach. As a result,
one may model the available bandwidth to the secondary
users as a random process taking value of 0 or 1. In
this paper, we investigate the effects of Rayleigh fading
environment on the capacity of AWGN point-to-point
channel. Afterwards, we also go beyond point to point
channels and analyze Multiple Access Channels. More
precisely, we derive the closed form expression of ergodic
capacity region of Multiple Access fading Channel with
two independent sources. To the best of our knowledge,
no prior work has investigated the ergodic capacity region
of Multiple Access Channel under Rayleigh fading
with the aforementioned approach. Numerical analysis are
conducted to validate our theoretical results. Interestingly,
numerical results indicate that, against the common sense,
capacity of Rayleigh fading environment channels are
higher than deterministic ones in Gaussian point-to-point
channels.
 
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Received: 2015/01/25 | Accepted: 2015/02/25 | Published: 2038/01/19

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