In this project, the Delay-Sensitive data capacity of the Wireless fading channel is explored under two distinct suppositions on the accessible transmitter channel state data (CSI). The principal situation accept consummate earlier learning of both the fundamental and spy channel picks up. Here, upper and lower limits on the protected delay constrained limit are inferred and appeared to be tight in the high flag to-clamor proportion (SNR) administration (for a wide class of channel circulations). In the second situation, just the principle channel CSI is thought to be accessible at the transmitter. Amazingly, under this suspicion, I build up the achievability of non-zero secure rate (for a wide class of channel circulations) under a strict delay limitation. In the two cases, our achievability contentions depend on a novel two phase approach that defeats the mystery blackout wonder saw in before works.
In this project, the Delay-Sensitive data capacity of the Wireless fading channel is explored under two distinct suppositions on the accessible transmitter channel state data (CSI). The principal situation accept consummate earlier learning of both the fundamental and spy channel picks up. Here, upper and lower limits on the protected delay constrained limit are inferred and appeared to be tight in the high flag to-clamor proportion (SNR) administration (for a wide class of channel circulations). In the second situation, just the principle channel CSI is thought to be accessible at the transmitter. Amazingly, under this suspicion, I build up the achievability of non-zero secure rate (for a wide class of channel circulations) under a strict delay limitation. In the two cases, our achievability contentions depend on a novel two phase approach that defeats the mystery blackout wonder saw in before works.
In this paper, the delay limited secrecy capacity of the flat fading channel is investigated under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the secure delay limited capacity are derived and shown to be tight in the high signal-to-noise ratio (SNR) regime (for a wide class of channel distributions). In the second scenario, only the main channel CSI is assumed to be available at the transmitter. Remarkably, under this assumption, we establish the achievability of non-zero secure rate (for a wide class of channel distributions) under a strict delay constraint. In the two cases, our achievability arguments are based on a novel two-stage approach that overcomes the secrecy outage phenomenon observed in earlier works.
In this paper, the delay limited secrecy capacity of the flat fading channel is investigated under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the secure delay limited capacity are derived and shown to be tight in the high signal-to-noise ratio (SNR) regime (for a wide class of channel distributions). In the second scenario, only the main channel CSI is assumed to be available at the transmitter. Remarkably, under this assumption, we establish the achievability of non-zero secure rate (for a wide class of channel distributions) under a strict delay constraint. In the two cases, our achievability arguments are based on a novel two-stage approach that overcomes the secrecy outage phenomenon observed in earlier works.
We investigate the delay limited secrecy capacity of the flat fading channel under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the delay limited secrecy capacity are derived, and shown to be tight in the high signal-to-noise ratio (SNR) regime. In the second scenario, only the main channel CSI is assumed to be available at the transmitter where, remarkably, we establish the achievability of a non-zero delay-limited secure rate, for a wide class of channel distributions, with a high probability. In the two cases, our achievability arguments are based on a novel two-stage key-sharing approach that overcomes the secrecy outage phenomenon observed in earlier works.
The rapid growth in wireless communication systems has provided a flexibility of communication and content that has had a transformative impact to all aspects of society.However, the broadcast nature of the wireless medium makes these systems vulnerable to passive attacks in which the adversary attempts to eavesdrop on the transmitted messages, and to active attacks in which the adversary can intelligently manipulate legitimate transmissions, both of which can jeopardize a myriad of critical wireless services.Hence, it is imperative to design wireless networks with safeguards in place to ensure their resilience to attacks.To that end, this dissertation provides various perspectives in the domain of information theoretic secrecy and authentication, which provably guarantees security, regardless of the computational capabilities of the adversary.We strive to bridge the gap between the information theory of security and the practically implementable protocols within this paradigm.We first consider point to point secure communication over flat fading wireless channels under delay constraint.We extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under different assumptions on the transmitter channel state information (CSI).The capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes.These keys are stored in a key buffer and used to secure delay sensitive data.We also characterize the optimal 4.5 Multiple Preauthenticated Helpers . . . . . . . . . . . . . . . . . . .
The concept of physical layer security builds on the pivotal idea of turning the channel's imperfections, such as noise and fading, into a source of security. This is established through appropriately designed coding techniques and signal processing strategies. In this vein, it has been shown that fading channels can enhance the transmission of confidential information and that a secure communication can be achieved even when the channel to the eavesdropper is better than the main channel. However, to fully benefit from what fading has to offer, the knowledge of the channel state information at the transmitter (CSIT) is of primordial importance. In practical wireless communication systems, CSIT is usually obtained, prior to data transmission, through CSI feedback sent by the receivers. The channel links over which this feedback information is sent can be either noisy, rate-limited, or delayed, leading to CSIT uncertainty. In this paper, we present a comprehensive review of recent and ongoing research works on physical layer security with CSIT uncertainty. We focus on both information theoretic and signal processing approaches to the topic when the uncertainty concerns the channel to the wiretapper or the channel to the legitimate receiver. Moreover, we present a classification of the research works based on the considered channel uncertainty. Mainly, we distinguish between the cases when the uncertainty comes from an estimation error of the CSIT, from a CSI feedback link with limited capacity, or from an outdated CSI.
This paper considers point-to-point secure communication over flat fading channels under an outage constraint. More specifically, we extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under two different assumptions on the transmitter channel state information (CSI). First, we find the outage secrecy capacity assuming that the transmitter has perfect knowledge of the legitimate and eavesdropper channel gains. In this scenario, the capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes. These keys are stored in a key buffer and later used to secure delay sensitive data using the Vernam's one time pad technique. We then extend our results to the more practical scenario where the transmitter is assumed to know only the legitimate channel gain. Here, our achievability arguments rely on privacy amplification techniques to generate secret key bits. In the two cases, we also characterize the optimal power control policies which, interestingly, turn out to be a judicious combination of channel inversion and the optimal ergodic strategy. Finally, we analyze the effect of key buffer overflow on the overall outage probability.