544 research outputs found
A New Design Paradigm for Secure Full-Duplex Multiuser Systems
We consider a full-duplex (FD) multiuser system where an FD base station (BS)
is designed to simultaneously serve both downlink (DL) and uplink (UL) users in
the presence of half-duplex eavesdroppers (Eves). The problem is to maximize
the minimum (max-min) secrecy rate (SR) among all legitimate users, where the
information signals at the FD-BS are accompanied with artificial noise to
debilitate the Eves' channels. To enhance the max-min SR, a major part of the
power budget should be allocated to serve the users with poor channel
qualities, such as those far from the FD-BS, undermining the SR for other
users, and thus compromising the SR per-user. In addition, the main obstacle in
designing an FD system is due to the self-interference (SI) and co-channel
interference (CCI) among users. We therefore propose an alternative solution,
where the FD-BS uses a fraction of the time block to serve near DL users and
far UL users, and the remaining fractional time to serve other users. The
proposed scheme mitigates the harmful effects of SI, CCI and multiuser
interference, and provides system robustness. The SR optimization problem has a
highly nonconcave and nonsmooth objective, subject to nonconvex constraints.
For the case of perfect channel state information (CSI), we develop a
low-complexity path-following algorithm, which involves only a simple convex
program of moderate dimension at each iteration. We show that our
path-following algorithm guarantees convergence at least to a local optimum.
Then, we extend the path-following algorithm to the cases of partially known
Eves' CSI, where only statistics of CSI for the Eves are known, and worst-case
scenario in which Eves can employ a more advanced linear decoder. The merit of
our proposed approach is further demonstrated by extensive numerical results.Comment: Accepted for publication in IEEE Journal on Selected Areas in
Communications (JSAC), 201
Multi-Objective Optimization for Power Efficient Full-Duplex Wireless Communication Systems
In this paper, we investigate power efficient resource allocation algorithm
design for multiuser wireless communication systems employing a full-duplex
(FD) radio base station for serving multiple half-duplex (HD) downlink and
uplink users simultaneously. We propose a multi-objective optimization
framework for achieving two conflicting yet desirable system design objectives,
i.e., total downlink transmit power minimization and total uplink transmit
power minimization, while guaranteeing the quality-of-service of all users. To
this end, the weighted Tchebycheff method is adopted to formulate a
multi-objective optimization problem (MOOP). Although the considered MOOP is
non-convex, we solve it optimally by semidefinite programming relaxation.
Simulation results not only unveil the trade-off between the total downlink and
the total uplink transmit power, but also confirm that the proposed FD system
provides substantial power savings over traditional HD systems.Comment: Accepted for presentation at the IEEE Globecom 2015, San Diego, CA,
USA, Dec. 201
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Sparse Signal Processing Concepts for Efficient 5G System Design
As it becomes increasingly apparent that 4G will not be able to meet the
emerging demands of future mobile communication systems, the question what
could make up a 5G system, what are the crucial challenges and what are the key
drivers is part of intensive, ongoing discussions. Partly due to the advent of
compressive sensing, methods that can optimally exploit sparsity in signals
have received tremendous attention in recent years. In this paper we will
describe a variety of scenarios in which signal sparsity arises naturally in 5G
wireless systems. Signal sparsity and the associated rich collection of tools
and algorithms will thus be a viable source for innovation in 5G wireless
system design. We will discribe applications of this sparse signal processing
paradigm in MIMO random access, cloud radio access networks, compressive
channel-source network coding, and embedded security. We will also emphasize
important open problem that may arise in 5G system design, for which sparsity
will potentially play a key role in their solution.Comment: 18 pages, 5 figures, accepted for publication in IEEE Acces
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