50,685 research outputs found
Multiple Access Channels with Generalized Feedback and Confidential Messages
This paper considers the problem of secret communication over a multiple
access channel with generalized feedback. Two trusted users send independent
confidential messages to an intended receiver, in the presence of a passive
eavesdropper. In this setting, an active cooperation between two trusted users
is enabled through using channel feedback in order to improve the communication
efficiency. Based on rate-splitting and decode-and-forward strategies,
achievable secrecy rate regions are derived for both discrete memoryless and
Gaussian channels. Results show that channel feedback improves the achievable
secrecy rates.Comment: To appear in the Proceedings of the 2007 IEEE Information Theory
Workshop on Frontiers in Coding Theory, Lake Tahoe, CA, September 2-6, 200
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
Design guidelines for spatial modulation
A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants
Capacity Bounds For Multi-User Channels With Feedback, Relaying and Cooperation
Recent developments in communications are driven by the goal of
achieving high data rates for wireless communication devices. To
achieve this goal, several new phenomena need to be investigated
from an information theoretic perspective. In this dissertation,
we focus on three of these phenomena: feedback, relaying and
cooperation. We study these phenomena for various multi-user
channels from an information theoretic point of view.
One of the aims of this dissertation is to study the performance
limits of simple wireless networks, for various forms of feedback
and cooperation. Consider an uplink communication system, where
several users wish to transmit independent data to a base-station.
If the base-station can send feedback to the users, one can expect
to achieve higher data-rates since feedback can enable cooperation
among the users. Another way to improve data-rates is to make use
of the broadcast nature of the wireless medium, where the users
can overhear each other's transmitted signals. This particular
phenomenon has garnered much attention lately, where users can
help in increasing each other's data-rates by utilizing the
overheard information. This overheard information can be
interpreted as a generalized form of feedback.
To take these several models of feedback and cooperation into
account, we study the two-user multiple access channel and the
two-user interference channel with generalized feedback. For all
these models, we derive new outer bounds on their capacity
regions. We specialize these results for noiseless feedback,
additive noisy feedback and user-cooperation models and show
strict improvements over the previously known bounds.
Next, we study state-dependent channels with rate-limited state
information to the receiver or to the transmitter. This
state-dependent channel models a practical situation of fading,
where the fade information is partially available to the receiver
or to the transmitter. We derive new bounds on the capacity of
such channels and obtain capacity results for a special sub-class
of such channels.
We study the effect of relaying by considering the parallel relay
network, also known as the diamond channel. The parallel relay
network considered in this dissertation comprises of a cascade of
a general broadcast channel to the relays and an orthogonal
multiple access channel from the relays to the receiver. We
characterize the capacity of the diamond channel, when the
broadcast channel is deterministic. We also study the diamond
channel with partially separated relays, and obtain capacity
results when the broadcast channel is either semi-deterministic or
physically degraded. Our results also demonstrate that feedback to
the relays can strictly increase the capacity of the diamond
channel.
In several sensor network applications, distributed lossless
compression of sources is of considerable interest. The presence
of adversarial nodes makes it important to design compression
schemes which serve the dual purpose of reliable source
transmission to legitimate nodes while minimizing the information
leakage to the adversarial nodes. Taking this constraint into
account, we consider information theoretic secrecy, where our aim
is to limit the information leakage to the eavesdropper. For this
purpose, we study a secure source coding problem with coded side
information from a helper to the legitimate user. We derive the
rate-equivocation region for this problem. We show that the helper
node serves the dual purpose of reducing the source transmission
rate and increasing the uncertainty at the adversarial node. Next,
we considered two different secure source coding models and
provide the corresponding rate-equivocation regions
- …