Secure Transmission in Amplify-and-Forward Diamond Networks with a Single Eavesdropper

Unicast communication over a network of $M$-parallel relays in the presence of an eavesdropper is considered. The relay nodes, operating under individual power constraints, amplify and forward the signals received at their inputs. The problem of the maximum secrecy rate achievable with AF relaying is addressed. Previous work on this problem provides iterative algorithms based on semidefinite relaxation. However, those algorithms result in suboptimal performance without any performance and convergence guarantees. We address this problem for three specific network models, with real-valued channel gains. We propose a novel transformation that leads to convex optimization problems. Our analysis leads to (i)a polynomial-time algorithm to compute the optimal secure AF rate for two of the models and (ii) a closed-form expression for the optimal secure rate for the other.Comment: 12pt font, 18 pages, 1 figure, conferenc

Robust Power Allocation and Outage Analysis for Secrecy in Independent Parallel Gaussian Channels

This letter studies parallel independent Gaussian channels with uncertain eavesdropper channel state information (CSI). Firstly, we evaluate the probability of zero secrecy rate in this system for (i) given instantaneous channel conditions and (ii) a Rayleigh fading scenario. Secondly, when non-zero secrecy is achievable in the low SNR regime, we aim to solve a robust power allocation problem which minimizes the outage probability at a target secrecy rate. We bound the outage probability and obtain a linear fractional program that takes into account the uncertainty in eavesdropper CSI while allocating power on the parallel channels. Problem structure is exploited to solve this optimization problem efficiently. We find the proposed scheme effective for uncertain eavesdropper CSI in comparison with conventional power allocation schemes.Comment: 4 pages, 2 figures. Author version of the paper published in IEEE Wireless Communications Letters. Published version is accessible at http://dx.doi.org/10.1109/LWC.2015.249734

SINR based Vertical Handoff Algorithm between GPRS and Wi-Fi Networks

Next generation wireless network is foreseen as the combination of heterogeneous wireless networks capable of providing enhanced services to mobile users. Vertical handoff is a crucial issue in providing service to mobile users, in a heterogeneous network. To maintain continuous service during vertical handoff period, the handoff procedure should consider the noise and interference in the networks. In this article, we have proposed an algorithm based on the received signal to inference plus noise ratio (SINR) for handoff between GPRS and Wi-Fi networks. Here SINR from Wi-Fi network is converted to the equivalent SINR of the GPRS network and vice-versa, so that the handoff algorithm can have the knowledge of achievable bandwidths in both the networks. This helps in taking a handoff decision. Simulation study on handoff between GPRS and Wi-Fi networks using QualNet showed that consideration of received SINR during the vertical handoff period maintains better system throughput than considering received signal strength (RSS) as handoff criteria

Potential anticancer peptides design from the cysteine rich plant defensins: An in silico approach

Cancer is the second leading cause of mortality worldwide preceded by cardiovascular diseases. The therapeutic approaches for drug developmentinclude the use of small molecules, antibodies, peptidesor short nucleic acid sequences. The peptide-based drugs have been developed to treat many diseases like cardiovascular diseases, cancer, metabolic disorders, immunological diseases and viral infections. More than 80 peptide drugs are already in the market. These therapeutic peptides have several important benefits over antibodies and proteins due to their small size, ease for chemical synthesis and further the ability to penetrate cell membrane. Furthermore, peptide drugs have high specificity, activity, and affinity. The plant defensins BcDef1, TPP3, NaD1, 2N2R and 2LR3 have been studied for their role in wide range of diseases. This study focussed on the conformation of plant defensins rich in disulfide bonds. The structure for BcDef1 has been predicted from the conformational ensemble. Then, we designed anticancer peptides from these defensins with computational methods. The designed anticancer peptides have been studied for their immunogenicity as well as homology with human proteome. The role of designed peptides has been suggested for interferon-gamma induction, the later has been shown to possess a very important role in cancer

A novel 13 residue acyclic peptide from the marine snail, Conus monile, targets potassium channels

A novel 13-residue peptide Mo1659 has been isolated from the venom of a vermivorous cone snail, Conus monile. HPLC fractions of the venom extract yielded an intense UV absorbing fraction with a mass of 1659 Da. De novo sequencing using both matrix assisted laser desorption and ionization and electrospray MS/MS methods together with analysis of proteolytic fragments successfully yielded the amino acid sequence, FHGGSWYRFPWGY-NH2. This was further confirmed by comparison with the chemically synthesized peptide and by conventional Edman sequencing. Mo1659 has an unusual sequence with a preponderance of aromatic residues and the absence of apolar, aliphatic residues like Ala, Val, Leu, and Ile. Mo1659 has no disulfide bridges distinguishing it from the conotoxins and bears no sequence similarity with any of the acyclic peptides isolated thus far from the venom of cone snails. Electrophysiological studies on the effect of Mo1659 on measured currents in dorsal root ganglion neurons suggest that the peptide targets non-inactivating voltage-dependent potassium channels

Novel peptides of therapeutic promise from Indian conidae

Highly structured small peptides are the major toxic constituents of the venom of cone snails, a family of widely distributed predatory marine molluscs. These animals use the venom for rapid prey immobilization. The peptide components in the venom target a wide variety of membrane-bound ion channels and receptors. Many have been found to be highly selective for a diverse range of mammalian ion channels and receptors associated with pain-signaling pathways. Their small size, structural stability, and target specificity make them attractive pharmacologic agents. A select number of laboratories mainly from the United States, Europe, Australia, Israel, and China have been engaged in intense drug discovery programs based on peptides from a few snail species. Coastal India has an estimated 20-30% of the known cone species; however, few serious studies have been reported so far. We have begun a comprehensive program for the identification and characterization of peptides from cone snails found in Indian Coastal waters. This presentation reviews our progress over the last 2 years. As expected from the evolutionary history of these venom components, our search has yielded novel peptides of therapeutic promise from the new species that we have studied