Enhancing wireless security via optimal cooperative jamming

In this work, we analyze the secrecy rate in a cooperative network, where a source node is assisted by relay nodes via cooperative jamming for delivering a secret message to the destination in the presence of an eavesdropper node. We consider the availability of both full and partial channel state information (CSI), and we take into account average power limitation at the relays as we formulate the rate maximization problem as a primal-dual problem. We derive the closed form solution for the full CSI case, and we show that the optimal solution allows the transmission of only one relay. For the partial CSI case, we define the concept of secrecy outage, where some of packets are intercepted by the eavesdropper, and we derive the secrecy outage probability and throughput in terms of average channel statistics. Due to the high nonlinearity of the secrecy throughput term, we propose a gradient update algorithm for obtaining the optimal power solutions for the partial CSI case. Our simulations demonstrate the gains of cooperative jamming over direct transmission for both full and partial CSI cases, where it is shown that the secrecy rate of the direct transmission is increased significantly, by %20−%80, when CJ is employed with our optimal power assignment algorithm

Optimal Design of Social Security Reforms

We argue that a privatization of the social security system, going from a Pay-As-You- Go to a Fully Funded system, can be interpreted as the explicit recognition of an implicit debt and there is no efficiency gain in doing so. As a consequence, potential efficiency gains upon reforming the system come from the elimination of distortions and the optimal management of that implicit debt. Based on that argument, this paper studies the optimal design of a social security privatization in a Pareto improving way. The government decides endogenously how to finance the transition and the welfare of the initial generations alive becomes policy constraint. We find that the government can design a Pareto improving reform that exhibits sizeable welfare gains, arising because of a reduction in labor supply distortions. In contrast, the welfare gain from reducing savings distortions is relatively small. Our approach explicitly provides quantitative policy prescriptions towards the policy design of future and maybe unavoidable social security reforms.

Optimal security-constrained power scheduling by Benders decomposition

This paper presents a Benders decomposition approach to determine the optimal day-ahead power scheduling in a pool-organized power system, taking into account dispatch, network and security constraints. The study model considers the daily market and the technical constraints resolution as two different and consecutive processes. The daily market is solved in a first stage subject to economical criteria exclusively and then, the constraints solution algorithm is applied to this initial dispatch through the redispatching method. The Benders partitioning algorithm is applied to this constraints solution process to obtain an optimal secure power scheduling. The constraints solution includes a full AC network and security model to incorporate voltages magnitudes as they are a critical factor in some real power systems. The algorithm determines the active power committed to each generator so as to minimize the energy redispatch cost subject to dispatch, network and security constraints. The solution also provides the reactive power output of the generators, the value of the transformers taps and the committed voltage control devices. The model has been tested in the IEEE 24-bus Reliability Test System and in an adapted IEEE 118-bus Test System. It is programmed in GAMS mathematical modeling language. Some relevant results are reported.Publicad

Quantum Cryptography: Security Criteria Reexamined

We find that the generally accepted security criteria are flawed for a whole class of protocols for quantum cryptography. This is so because a standard assumption of the security analysis, namely that the so-called square-root measurement is optimal for eavesdropping purposes, is not true in general. There are rather large parameter regimes in which the optimal measurement extracts substantially more information than the square-root measurement.Comment: 4 pages, 4 figures. No substantial changes. Updated version as published in PR

Should ministerial arrangements for domestic security be changed?

Are Australia\u27s ministerial arrangements for managing domestic security optimal? This paper examines this question as a debate. Overview The recent increase in Australia’s terrorism alert, reported prime ministerial concern over national security arrangements, major increases in counterterrorism funding and operational success against people smuggling have raised a new question in Canberra: are our arrangements for managing domestic security optimal? This paper examines this question as a debate. Presenting the case for change is ASPI senior analyst David Connery. He gives five reasons why change is needed, before proposing a new split in which a Minister for Security and Resilience takes over responsibility for enforcing Australia’s domestic security and emergency management laws. Peter Jennings, ASPI’s executive director, presents a case for the status quo, arguing that the National Security Committee of Cabinet (NSC) is more important in ensuring coordinated security policy than the division of responsibilities among its ministers

The Optimal Level of Social Security Benefits

The optimal level of Social Security benefits depends on balancing the protection that these benefits offer to those who have not provided adequately for their own old age against the welfare costs of distorting economic behavior. The primary such cost is the distortion in private saving. The present paper derives the level of Social Security benefits that is optimal in three basic cases. In the first section of the paper, the optimal level of benefits is derived for an economy in which all individuals do not anticipate retirement at all and therefore do not save. The second and third sections then derive the optimal benefits for economies with two different definitions of attitudes toward retirement and saving.