10 research outputs found
Location-Based Beamforming for Rician Wiretap Channels
We propose a location-based beamforming scheme for wiretap channels, where a
source communicates with a legitimate receiver in the presence of an
eavesdropper. We assume that the source and the eavesdropper are equipped with
multiple antennas, while the legitimate receiver is equipped with a single
antenna. We also assume that all channels are in a Rician fading environment,
the channel state information from the legitimate receiver is perfectly known
at the source, and that the only information on the eavesdropper available at
the source is her location. We first describe how the beamforming vector that
minimizes the secrecy outage probability of the system is obtained,
illustrating its dependence on the eavesdropper's location. We then derive an
easy-to-compute expression for the secrecy outage probability when our proposed
location-based beamforming is adopted. Finally, we investigate the impact
location uncertainty has on the secrecy outage probability, showing how our
proposed solution can still allow for secrecy even when the source has limited
information on the eavesdropper's location.Comment: 6 pages, 4 figure
INVESTIGATION OF CAPACITY GAINS IN MIMO CORRELATED RICIAN FADING CHANNELS SYSTEMS
This paper investigate the effect of Rician fading and correlation on the capacity and diversity of MIMO channels. The use of antenna arrays at both sides of the wireless communication link (MIMO systems) can increase channel capacity provided the propagation medium is rich scattering or Rayleigh fading and the antenna arrays at both sides are uncorrelated. However, the presence of line-of-sight (LOS) component and correlation of real world wireless channels may affect the system performance. Along with that we also investigate power distribution methods for higher capacity gains and effect of CSI at the transmitter on the capacity for range of SNR. Our investigation follows capacity gain as function of number of antennas and signal-to-noise (SNR) power ratio Block and frequency nonselective Rician fading channel is assumed, and the effect of Rician factor (L) and the correlation parameter (Ļ) on the capacity and diversity gains of MIMO channels are found. Inde
Location-Based Beamforming and Physical Layer Security in Rician Wiretap Channels
We propose a new location-based beamforming (LBB) scheme for wiretap
channels, where a multi-antenna source communicates with a single-antenna
legitimate receiver in the presence of a multi-antenna eavesdropper. We assume
that all channels are in a Rician fading environment, the channel state
information from the legitimate receiver is perfectly known at the source, and
that the only information on the eavesdropper available at the source is her
location. We first describe how the optimal beamforming vector that minimizes
the secrecy outage probability of the system is obtained, illustrating its
dependence on the eavesdropper's location. We then derive an easy-to-compute
expression for the secrecy outage probability when our proposed LBB scheme is
adopted. We also consider the positive impact a friendly jammer can have on our
beamforming solution, showing how the path to optimality remains the same.
Finally, we investigate the impact of location uncertainty on the secrecy
outage probability, showing how our solution can still allow for secrecy even
when the source only has a noisy estimate of the eavesdropper's location. Our
work demonstrates how a multi-antenna array, operating in the most general
channel conditions and most likely system set-up, can be configured rapidly in
the field so as to deliver an optimal physical layer security solution.Comment: 11 pages, 8 figures. Accepted for publication in IEEE Transactions on
Wireless Communications. arXiv admin note: substantial text overlap with
arXiv:1510.0856
Secrecy Performance Analysis of Location-Based Beamforming in Rician Wiretap Channels
We propose a new optimal Location-Based Beamforming (LBB) scheme for the
wiretap channel, where both the main channel and the eavesdropper's channel are
subject to Rician fading. In our LBB scheme the two key inputs are the location
of the legitimate receiver and the location of the potential eavesdropper.
Notably, our scheme does not require as direct inputs any channel state
information of the main channel or the eavesdropper's channel, making it easy
to deploy in a host of application settings in which the location inputs are
known. Our beamforming solution assumes a multiple-antenna transmitter, a
multiple-antenna eavesdropper, and a single-antenna receiver, and its aim is to
maximize the physical layer security of the channel. To obtain our solution we
first derive the secrecy outage probability of the LBB scheme in a closed-form
expression that is valid for arbitrary values of the Rician K-factors of the
main channel and the eavesdropper's channel. Using this expression we then
determine the location-based beamformer solution that minimizes the secrecy
outage probability. To assess the usefulness of our new scheme, and to quantify
the value of the location information to the beamformer, we compare our scheme
to other schemes, some of which do not utilize any location information. Our
new beamformer solution provides optimal physical layer security for a wide
range of location-based applications.Comment: 10 pages, 6 figure
Joint Beamforming and Power Control in Coordinated Multicell: Max-Min Duality, Effective Network and Large System Transition
This paper studies joint beamforming and power control in a coordinated
multicell downlink system that serves multiple users per cell to maximize the
minimum weighted signal-to-interference-plus-noise ratio. The optimal solution
and distributed algorithm with geometrically fast convergence rate are derived
by employing the nonlinear Perron-Frobenius theory and the multicell network
duality. The iterative algorithm, though operating in a distributed manner,
still requires instantaneous power update within the coordinated cluster
through the backhaul. The backhaul information exchange and message passing may
become prohibitive with increasing number of transmit antennas and increasing
number of users. In order to derive asymptotically optimal solution, random
matrix theory is leveraged to design a distributed algorithm that only requires
statistical information. The advantage of our approach is that there is no
instantaneous power update through backhaul. Moreover, by using nonlinear
Perron-Frobenius theory and random matrix theory, an effective primal network
and an effective dual network are proposed to characterize and interpret the
asymptotic solution.Comment: Some typos in the version publised in the IEEE Transactions on
Wireless Communications are correcte
A unified complex noncentral Wishart type distribution inspired by massive MIMO systems
Please read abstract in the article.The National Research Foundation of South Africahttps://link.springer.com/journal/40488am2019Statistic
Finite Random Matrix Theory Analysis of Multiple Antenna Communication Systems
Multiple-antenna systems are capable of providing substantial improvement to wireless communication networks, in terms of
data rate and reliability. Without utilizing extra spectrum or power resources, multiple-antenna technology has already been supported
in several wireless communication standards, such as LTE, WiFi and WiMax. The surging popularity and enormous prospect of
multiple-antenna technology require a better understanding to its fundamental performance over practical environments.
Motivated by this, this thesis provides analytical characterizations of several seminal performance measures in advanced multiple-antenna
systems. The analytical derivations are mainly based on finite dimension random matrix theory and a collection of novel random matrix theory
results are derived.
The closed-form probability density function of the output of multiple-input multiple-output (MIMO) block-fading channels is studied.
In contrast to the existing results, the proposed expressions are very general, applying for arbitrary number of antennas, arbitrary signal-to-noise
ratio and multiple classical fading models. Results are presented assuming two input structures in the system: the independent identical distributed
(i.i.d.) Gaussian input and a product form input. When the channel is fed by the i.i.d. Gaussian input, analysis is focused on the channel matrices
whose Gramian is unitarily invariant. When the channel is fed by a product form input, analysis is conducted with respect to two capacity-achieving
input structures that are dependent upon the relationship between the coherence length and the number of antennas. The mutual information
of the systems can be computed numerically from the pdf expression of the output. The computation is relatively easy to handle, avoiding the
need of the straight Monte-Carlo computation which is not feasible in large-dimensional networks.
The analytical characterization of the output pdf of a single-user MIMO block-fading channels with imperfect channel state information at the receiver
is provided. The analysis is carried out under the assumption of a product structure for the input. The model can be thought of as a perturbation
of the case where the statistics of the channel are perfectly known. Specifically, the average singular values of the channel are given, while the
channel singular vectors are assumed to be isotropically distributed on the unitary groups of dimensions given by the number of transmit and
receive antennas. The channel estimate is affected by a Gaussian distributed error, which is modeled as a matrix with i.i.d. Gaussian entries of
known covariance.
The ergodic capacity of an amplify-and-forward (AF) MIMO relay network over asymmetric channels is investigated. In particular, the source-relay
and relay-destination channels undergo Rayleigh and Rician fading, respectively. Considering arbitrary-rank means for the relay-destination channel,
the marginal distribution of an unordered eigenvalue of the cascaded AF channel is presented, thus the analytical expression of the ergodic capacity
of the system is obtained. The results indicate the impact of the signal-to-noise ratio and of the Line-of-Sight component on such asymmetric
relay network