758 research outputs found
Outage Performance Analysis of Multicarrier Relay Selection for Cooperative Networks
In this paper, we analyze the outage performance of two multicarrier relay
selection schemes, i.e. bulk and per-subcarrier selections, for two-hop
orthogonal frequency-division multiplexing (OFDM) systems. To provide a
comprehensive analysis, three forwarding protocols: decode-and-forward (DF),
fixed-gain (FG) amplify-and-forward (AF) and variable-gain (VG) AF relay
systems are considered. We obtain closed-form approximations for the outage
probability and closed-form expressions for the asymptotic outage probability
in the high signal-to-noise ratio (SNR) region for all cases. Our analysis is
verified by Monte Carlo simulations, and provides an analytical framework for
multicarrier systems with relay selection
Ergodic Capacity Analysis of Amplify-and-Forward MIMO Dual-Hop Systems
This paper presents an analytical characterization of the ergodic capacity of
amplify-and-forward (AF) MIMO dual-hop relay channels, assuming that the
channel state information is available at the destination terminal only. In
contrast to prior results, our expressions apply for arbitrary numbers of
antennas and arbitrary relay configurations. We derive an expression for the
exact ergodic capacity, simplified closed-form expressions for the high SNR
regime, and tight closed-form upper and lower bounds. These results are made
possible to employing recent tools from finite-dimensional random matrix theory
to derive new closed-form expressions for various statistical properties of the
equivalent AF MIMO dual-hop relay channel, such as the distribution of an
unordered eigenvalue and certain random determinant properties. Based on the
analytical capacity expressions, we investigate the impact of the system and
channel characteristics, such as the antenna configuration and the relay power
gain. We also demonstrate a number of interesting relationships between the
dual-hop AF MIMO relay channel and conventional point-to-point MIMO channels in
various asymptotic regimes.Comment: 40 pages, 9 figures, Submitted to to IEEE Transactions on Information
Theor
Performance Analysis of Optimal Single Stream Beamforming in MIMO Dual-Hop AF Systems
This paper investigates the performance of optimal single stream beamforming
schemes in multiple-input multiple-output (MIMO) dual-hop amplify-and-forward
(AF) systems. Assuming channel state information is not available at the source
and relay, the optimal transmit and receive beamforming vectors are computed at
the destination, and the transmit beamforming vector is sent to the transmitter
via a dedicated feedback link. Then, a set of new closed-form expressions for
the statistical properties of the maximum eigenvalue of the resultant channel
is derived, i.e., the cumulative density function (cdf), probability density
function (pdf) and general moments, as well as the first order asymptotic
expansion and asymptotic large dimension approximations. These analytical
expressions are then applied to study three important performance metrics of
the system, i.e., outage probability, average symbol error rate and ergodic
capacity. In addition, more detailed treatments are provided for some important
special cases, e.g., when the number of antennas at one of the nodes is one or
large, simple and insightful expressions for the key parameters such as
diversity order and array gain of the system are derived. With the analytical
results, the joint impact of source, relay and destination antenna numbers on
the system performance is addressed, and the performance of optimal beamforming
schemes and orthogonal space-time block-coding (OSTBC) schemes are compared.
Results reveal that the number of antennas at the relay has a great impact on
how the numbers of antennas at the source and destination contribute to the
system performance, and optimal beamforming not only achieves the same maximum
diversity order as OSTBC, but also provides significant power gains over OSTBC.Comment: to appear in IEEE Journal on Selected Areas in Communications special
issue on Theories and Methods for Advanced Wireless Relay
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
Amplify-and-Forward Relaying in Two-Hop Diffusion-Based Molecular Communication Networks
This paper studies a three-node network in which an intermediate
nano-transceiver, acting as a relay, is placed between a nano-transmitter and a
nano-receiver to improve the range of diffusion-based molecular communication.
Motivated by the relaying protocols used in traditional wireless communication
systems, we study amplify-and-forward (AF) relaying with fixed and variable
amplification factor for use in molecular communication systems. To this end,
we derive a closed-form expression for the expected end-to-end error
probability. Furthermore, we derive a closed-form expression for the optimal
amplification factor at the relay node for minimization of an approximation of
the expected error probability of the network. Our analytical and simulation
results show the potential of AF relaying to improve the overall performance of
nano-networks.Comment: 7 pages, 6 figures, 1 table. Submitted to the 2015 IEEE Global
Communications Conference (GLOBECOM) on April 15, 201
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