1,057 research outputs found
Beacon-Assisted Spectrum Access with Cooperative Cognitive Transmitter and Receiver
Spectrum access is an important function of cognitive radios for detecting
and utilizing spectrum holes without interfering with the legacy systems. In
this paper we propose novel cooperative communication models and show how
deploying such cooperations between a pair of secondary transmitter and
receiver assists them in identifying spectrum opportunities more reliably.
These cooperations are facilitated by dynamically and opportunistically
assigning one of the secondary users as a relay to assist the other one which
results in more efficient spectrum hole detection. Also, we investigate the
impact of erroneous detection of spectrum holes and thereof missing
communication opportunities on the capacity of the secondary channel. The
capacity of the secondary users with interference-avoiding spectrum access is
affected by 1) how effectively the availability of vacant spectrum is sensed by
the secondary transmitter-receiver pair, and 2) how correlated are the
perceptions of the secondary transmitter-receiver pair about network spectral
activity. We show that both factors are improved by using the proposed
cooperative protocols. One of the proposed protocols requires explicit
information exchange in the network. Such information exchange in practice is
prone to wireless channel errors (i.e., is imperfect) and costs bandwidth loss.
We analyze the effects of such imperfect information exchange on the capacity
as well as the effect of bandwidth cost on the achievable throughput. The
protocols are also extended to multiuser secondary networks.Comment: 36 pages, 6 figures, To appear in IEEE Transaction on Mobile
Computin
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
Interference Alignment for Cognitive Radio Communications and Networks: A Survey
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Interference alignment (IA) is an innovative wireless transmission strategy that has shown to be a promising technique for achieving optimal capacity scaling of a multiuser interference channel at asymptotically high-signal-to-noise ratio (SNR). Transmitters exploit the availability of multiple signaling dimensions in order to align their mutual interference at the receivers. Most of the research has focused on developing algorithms for determining alignment solutions as well as proving interference alignment’s theoretical ability to achieve the maximum degrees of freedom in a wireless network. Cognitive radio, on the other hand, is a technique used to improve the utilization of the radio spectrum by opportunistically sensing and accessing unused licensed frequency spectrum, without causing harmful interference to the licensed users. With the increased deployment of wireless services, the possibility of detecting unused frequency spectrum becomes diminished. Thus, the concept of introducing interference alignment in cognitive radio has become a very attractive proposition. This paper provides a survey of the implementation of IA in cognitive radio under the main research paradigms, along with a summary and analysis of results under each system model.Peer reviewe
- …