382 research outputs found
On Amplify-and-Forward Relaying Over Hyper-Rayleigh Fading Channels
Relayed transmission holds promise for the next generation of wireless communication systems due to the performance gains it can provide over non-cooperative systems. Recently hyper-Rayleigh fading, which represents fading conditions more severe than Rayleigh fading, has received attention in the context of many practical communication scenarios. Though power allocation for Amplify-and-Forward (AF) relaying networks has been studied in the literature, a theoretical analysis of the power allocation problem for hyper-Rayleigh fading channels is a novel contribution of this work. We develop an optimal power allocation (OPA) strategy for a dual-hop AF relaying network in which the relay-destination link experiences hyper-Rayleigh fading. A new closed-form expression for the average signal-to-noise ratio (SNR) at destination is derived and it is shown to provide a new upper-bound on the average SNR at destination, which outperforms a previously proposed upper-bound based on the well-known harmonic-geometric mean inequality. An OPA across the source and relay nodes, subject to a sum-power constraint, is proposed and it is shown to provide measurable performance gains in average SNR and SNR outage at the destination relative to the case of equal power allocation
Outage Probability of Dual-Hop Selective AF With Randomly Distributed and Fixed Interferers
The outage probability performance of a dual-hop amplify-and-forward
selective relaying system with global relay selection is analyzed for
Nakagami- fading channels in the presence of multiple interferers at both
the relays and the destination. Two different cases are considered. In the
first case, the interferers are assumed to have random number and locations.
Outage probability using the generalized Gamma approximation (GGA) in the form
of one-dimensional integral is derived. In the second case, the interferers are
assumed to have fixed number and locations. Exact outage probability in the
form of one-dimensional integral is derived. For both cases, closed-form
expressions of lower bounds and asymptotic expressions for high
signal-to-interference-plus-noise ratio are also provided. Simplified
closed-form expressions of outage probability for special cases (e.g., dominant
interferences, i.i.d. interferers, Rayleigh distributed signals) are studied.
Numerical results are presented to show the accuracy of our analysis by
examining the effects of the number and locations of interferers on the outage
performances of both AF systems with random and fixed interferers.Comment: 35 pages, 11 figures, accepted with minor revisions for publication
as a regular paper in the IEEE Transactions on Vehicular Technology on
21/09/201
Outage Probability of Dual-Hop Multiple Antenna AF Relaying Systems with Interference
This paper presents an analytical investigation on the outage performance of
dual-hop multiple antenna amplify-and-forward relaying systems in the presence
of interference. For both the fixed-gain and variable-gain relaying schemes,
exact analytical expressions for the outage probability of the systems are
derived. Moreover, simple outage probability approximations at the high signal
to noise ratio regime are provided, and the diversity order achieved by the
systems are characterized. Our results suggest that variable-gain relaying
systems always outperform the corresponding fixed-gain relaying systems. In
addition, the fixed-gain relaying schemes only achieve diversity order of one,
while the achievable diversity order of the variable-gain relaying scheme
depends on the location of the multiple antennas.Comment: Accepted to appear in IEEE Transactions on Communication
Exact performance analysis of dual-hop semi-blind AF relaying over arbitrary nakagami-m fading channels
Relay transmission is promising for future wireless systems due to its significant cooperative diversity gain. The performance of dual-hop semi-blind amplify-and-forward (AF) relaying systems was extensively investigated, for transmissions over Rayleigh fading channels or Nakagami-m fading channels with integer fading parameter. For the general Nakagami-m fading with arbitrary m values, the exact closed-form system performance analysis is more challenging. In this paper, we explicitly derive the moment generation function (MGF), probability density function (PDF) and moments of the end-to-end signal-to-noise ratio (SNR) over arbitrary Nakagami-m fading channels with semi-blind AF relay. With these results, the system performance evaluation in terms of outage probability, average symbol error probability, ergodic capacity and diversity order, is conducted. The analysis developed in this paper applies to any semi-blind AF relaying systems with fixed relay gain, and two major strategies for computing the relay gain are compared in terms of system performance. All analytical results are corroborated by simulation results and they are shown to be efficient tools to evaluate system performance. © 2011 IEEE.published_or_final_versio
A novel equivalent definition of modified Bessel functions for performance analysis of multi-hop wireless communication systems
A statistical model is derived for the equivalent signal-to-noise ratio of the Source-to-Relay-to-Destination (S-R-D) link for Amplify-and-Forward (AF) relaying systems that are subject to block Rayleigh-fading. The probability density function and the cumulated density function of the S-R-D link SNR involve modified Bessel functions of the second kind. Using fractional-calculus mathematics, a novel approach is introduced to rewrite those Bessel functions (and the statistical model of the S-R-D link SNR) in series form using simple elementary functions. Moreover, a statistical characterization of the total receive-SNR at the destination, corresponding to the S-R-D and the S-D link SNR, is provided for a more general relaying scenario in which the destination receives signals from both the relay and the source and processes them using maximum ratio combining (MRC). Using the novel statistical model for the total receive SNR at the destination, accurate and simple analytical expressions for the outage probability, the bit error probability, and the ergodic capacity are obtained. The analytical results presented in this paper provide a theoretical framework to analyze the performance of the AF cooperative systems with an MRC receiver
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