6,329 research outputs found
Analytic solutions to a Marcum Q-function-based integral and application in energy detection of unknown signals over multipath fading channels
This work presents analytic solutions for a useful integral in wireless
communications, which involves the Marcum function in combination with an
exponential function and arbitrary power terms. The derived expressions have a
rather simple algebraic representation which renders them convenient both
analytically and computationally. Furthermore, they can be useful in wireless
communications and particularly in the context of cognitive radio
communications and radar systems, where this integral is often encountered. To
this end, we derive novel expressions for the probability of detection in
energy detection based spectrum sensing over fading channels.
These expressions are given in closed-form and are subsequently employed in
analyzing the effects of generalised multipath fading conditions in cognitive
radio systems. As expected, it is shown that the detector is highly dependent
upon the severity of fading conditions as even slight variation of the fading
parameters affect the corresponding performance significantly.Comment: Latest/Preprint Versio
MIMO Networks: the Effects of Interference
Multiple-input/multiple-output (MIMO) systems promise enormous capacity
increase and are being considered as one of the key technologies for future
wireless networks. However, the decrease in capacity due to the presence of
interferers in MIMO networks is not well understood. In this paper, we develop
an analytical framework to characterize the capacity of MIMO communication
systems in the presence of multiple MIMO co-channel interferers and noise. We
consider the situation in which transmitters have no information about the
channel and all links undergo Rayleigh fading. We first generalize the known
determinant representation of hypergeometric functions with matrix arguments to
the case when the argument matrices have eigenvalues of arbitrary multiplicity.
This enables the derivation of the distribution of the eigenvalues of Gaussian
quadratic forms and Wishart matrices with arbitrary correlation, with
application to both single user and multiuser MIMO systems. In particular, we
derive the ergodic mutual information for MIMO systems in the presence of
multiple MIMO interferers. Our analysis is valid for any number of interferers,
each with arbitrary number of antennas having possibly unequal power levels.
This framework, therefore, accommodates the study of distributed MIMO systems
and accounts for different positions of the MIMO interferers.Comment: Submitted to IEEE Trans. on Info. Theor
Asymptotic Mutual Information Statistics of Separately-Correlated Rician Fading MIMO Channels
Precise characterization of the mutual information of MIMO systems is
required to assess the throughput of wireless communication channels in the
presence of Rician fading and spatial correlation. Here, we present an
asymptotic approach allowing to approximate the distribution of the mutual
information as a Gaussian distribution in order to provide both the average
achievable rate and the outage probability. More precisely, the mean and
variance of the mutual information of the separatelycorrelated Rician fading
MIMO channel are derived when the number of transmit and receive antennas grows
asymptotically large and their ratio approaches a finite constant. The
derivation is based on the replica method, an asymptotic technique widely used
in theoretical physics and, more recently, in the performance analysis of
communication (CDMA and MIMO) systems. The replica method allows to analyze
very difficult system cases in a comparatively simple way though some authors
pointed out that its assumptions are not always rigorous. Being aware of this,
we underline the key assumptions made in this setting, quite similar to the
assumptions made in the technical literature using the replica method in their
asymptotic analyses. As far as concerns the convergence of the mutual
information to the Gaussian distribution, it is shown that it holds under some
mild technical conditions, which are tantamount to assuming that the spatial
correlation structure has no asymptotically dominant eigenmodes. The accuracy
of the asymptotic approach is assessed by providing a sizeable number of
numerical results. It is shown that the approximation is very accurate in a
wide variety of system settings even when the number of transmit and receive
antennas is as small as a few units.Comment: - submitted to the IEEE Transactions on Information Theory on Nov.
19, 2006 - revised and submitted to the IEEE Transactions on Information
Theory on Dec. 19, 200
Diversity, Coding, and Multiplexing Trade-Off of Network-Coded Cooperative Wireless Networks
In this paper, we study the performance of network-coded cooperative
diversity systems with practical communication constraints. More specifically,
we investigate the interplay between diversity, coding, and multiplexing gain
when the relay nodes do not act as dedicated repeaters, which only forward data
packets transmitted by the sources, but they attempt to pursue their own
interest by forwarding packets which contain a network-coded version of
received and their own data. We provide a very accurate analysis of the Average
Bit Error Probability (ABEP) for two network topologies with three and four
nodes, when practical communication constraints, i.e., erroneous decoding at
the relays and fading over all the wireless links, are taken into account.
Furthermore, diversity and coding gain are studied, and advantages and
disadvantages of cooperation and binary Network Coding (NC) are highlighted.
Our results show that the throughput increase introduced by NC is offset by a
loss of diversity and coding gain. It is shown that there is neither a coding
nor a diversity gain for the source node when the relays forward a
network-coded version of received and their own data. Compared to other results
available in the literature, the conclusion is that binary NC seems to be more
useful when the relay nodes act only on behalf of the source nodes, and do not
mix their own packets to the received ones. Analytical derivation and findings
are substantiated through extensive Monte Carlo simulations.Comment: IEEE International Conference on Communications (ICC), 2012. Accepted
for publication and oral presentatio
A New Framework for the Performance Analysis of Wireless Communications under Hoyt (Nakagami-q) Fading
(c) 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. DOI:10.1109/TIT.2017.2655342We present a novel relationship between the distribution of circular and non-circular complex Gaussian random variables. Specifically, we show that the distribution of the squared norm of a non-circular complex Gaussian random variable, usually referred to as the squared Hoyt distribution, can be constructed from a conditional exponential distribution. From this fundamental connection we introduce a new approach, the Hoyt transform method, that allows to analyze the performance of a wireless link under Hoyt (Nakagami-q) fading in a very simple way. We illustrate that many performance metrics for Hoyt fading can be calculated by leveraging well-known results for Rayleigh fading and only performing a finite-range integral. We use this technique to obtain novel results for some information and communication-theoretic metrics in Hoyt fading channels.Universidad de Málaga. Campus de Execelencia Internacional. AndalucÃa Tech
An Upper Bound on Multi-hop Transmission Capacity with Dynamic Routing Selection
This paper develops upper bounds on the end-to-end transmission capacity of
multi-hop wireless networks. Potential source-destination paths are dynamically
selected from a pool of randomly located relays, from which a closed-form lower
bound on the outage probability is derived in terms of the expected number of
potential paths. This is in turn used to provide an upper bound on the number
of successful transmissions that can occur per unit area, which is known as the
transmission capacity. The upper bound results from assuming independence among
the potential paths, and can be viewed as the maximum diversity case. A useful
aspect of the upper bound is its simple form for an arbitrary-sized network,
which allows insights into how the number of hops and other network parameters
affect spatial throughput in the non-asymptotic regime. The outage probability
analysis is then extended to account for retransmissions with a maximum number
of allowed attempts. In contrast to prevailing wisdom, we show that
predetermined routing (such as nearest-neighbor) is suboptimal, since more hops
are not useful once the network is interference-limited. Our results also make
clear that randomness in the location of relay sets and dynamically varying
channel states is helpful in obtaining higher aggregate throughput, and that
dynamic route selection should be used to exploit path diversity.Comment: 14 pages, 5 figures, accepted to IEEE Transactions on Information
Theory, 201
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