Performance analysis of cooperative relay networks in presence of interference

In the past decade, cooperative communication has emerged as an attractive technique for overcoming the shortcomings of point-to-point wireless communications systems. Cooperative relaying improves the performance of wireless networks by forming an array of multiple independent virtual sources transmitting the same information as the source node. In addition, when relays are deployed near the edge of the network, they can provide additional coverage in network dead spots. Interference in the network can also be reduced in cooperative communications systems as the nodes can transmit at lower power levels compared to equivalent point-to-point communications systems. Optimum design of a cooperative network requires an accurate understanding of all factors affecting performance. In order to parameterize the performance of cooperative systems, this thesis introduces mathematical models for different performance metrics, such as symbol error probability, outage probability and random coding error exponent, in order to analytically estimate network capacity. A dual-hop network is introduced as the most basic type of relay network. Random coding error exponent results have been obtained using this simple network model are presented along with corresponding channel capacity estimates based on the assumption of Gaussian input codes. Next, a general multihop network error and outage performance model are developed. Detailed mathematical and statistical models for interference relay networks are presented. The basic statistical parameters, cumulative distribution function and probability density function for interference cooperative dual hop relay networks are derived and explored. A partial formulation for the random coding error exponent (RCEE) result is also presented. Simulation results over Rayleigh and Nakagami-m fading channel models are included in each chapter for all of the selected performance metrics in order to validate the theoretical analysis, under the assumption that channels are flat over the duration of one symbol transmission. These results are in close agreement with the predictions of the analytical models.University of Technology, Sydney. Faculty of Engineering and Information Technology

Error exponent of amplify and forward relay networks in presence of I.I.D. interferers

© 2014 IEEE. In this paper, we derive the random coding error exponent of amplify-and-forward (AF) relay networks in presence of arbitrary number of independent and identically distributed (i.i.d.) interferers both at the relay and the destination. Multiuser networks are common examples of interference limited networks. We derive the ergodic capacity of the network and present simulation results on the performance of the network where we compare the capacity and error exponent performance of interference limited networks with noise limited networks. Numerical results show that noise limited networks outperform interference limited networks even when only a very few interferers exist in the network

Method of producing water-soluble glucuronic acid derivatives of vitamin A

Water soluble glucuronic acid derivatives of vitamin A, including retinoyl β-glucuronide and retinyl β-glucuronide, having in vivo activity comparable to retinoicacid and retinol and methods of their preparation are disclosed

Dual role of nNOS in ischemic injury and preconditioning

<p>Abstract</p> <p>Background</p> <p>Nitric oxide (NO) is cardioprotective and a mediator of ischemic preconditioning (IP). Endothelial nitric oxide synthase (eNOS) is protective against myocardial ischemic injury and a component of IP but the role and location of neuronal nitric oxide synthase (nNOS) remains unclear. Therefore, the aims of these studies were to: (i) investigate the role of nNOS in ischemia/reoxygenation-induced injury and IP, (ii) determine whether its effect is species-dependent, and (iii) elucidate the relationship of nNOS with mitoK_ATPchannels and p38MAPK, two key components of IP transduction pathway.</p> <p>Results</p> <p>Ventricular myocardial slices from rats and wild and nNOS knockout mice, and right atrial myocardial slices from human were subjected to 90 min ischemia and 120 min reoxygenation (37°C). Specimens were randomized to receive various treatments (n = 6/group). Both the provision of exogenous NO and the inhibition of endogenous NO production significantly reduced tissue injury (creatine kinase release, cell necrosis and apoptosis), an effect that was species-independent. The cardioprotection seen with nNOS inhibition was as potent as that of IP, however, in nNOS knockout mice the cardioprotective effect of non-selective NOS (L-NAME) and selective nNOS inhibition and also that of IP was blocked while the benefit of exogenous NO remained intact. Additional studies revealed that the cardioprotection afforded by exogenous NO and by inhibition of nNOS were unaffected by the mitoK_ATPchannel blocker 5-HD, although it was abrogated by p38MAPK blocker SB203580.</p> <p>Conclusions</p> <p>nNOS plays a dual role in ischemia/reoxygenation in that its presence is necessary to afford cardioprotection by IP and its inhibition reduces myocardial ischemic injury. The role of nNOS is species-independent and exerted downstream of the mitoK_ATPchannels and upstream of p38MAPK.</p

Retinoic acid glucuronide preparations for application to the skin

A method and preparation are described for treating human skin with retinoic acid glucuronide (RAG) in a topical carrier. For treatment of acne or wrinkled skin, RAG can be applied in an effective amount which is nonirritating to the skin. Retinoid dermatitis, an objectionable side effect of topical application of retinoid compounds, can thereby be avoided

Non-teratogenic vitamin A preparation for women of child-bearing age

For treatment of acne the glucuronide of retinoic acid (retinoyl β-glucuronide) is orally administered to women of child-bearing age who are capable of conception. This therapy is safer than the oral administration of retinoic acid because retinoic acid glucuronide is essentially non-teratogenic at dose levels effective for the acne treatment. The retinoic acid glucuronide can be in all-trans or 13-cis form

Ionization Cross-Sections of Atoms and Molecules by Electron Impact

Apparent ionization cross-sections of,several atoms and molecules for 70 ev electrons have been measured with the help of a mass spectrometer. By introducing a simple correction an attempt has been made to improve the method of Otvos and Stevenson for the calculation of the ionization cross-sections of atoms and molecules. With this correction, the additivity postulate for the molecular ionization cross-sections appears to hold better the additivity postulate for tho molecular ionization cross-sections appears to hold better

Outage Probability Analysis of Dual Hop Relay Networks in Presence of Interference

Cooperative relaying improves the performance of wireless networks by forming a network of multiple independent virtual sources transmitting the same information as the source node. However, interference induced in the network reduces the performance of cooperative communications. In this work the statistical properties, the cumulative distribution function (CDF) and the probability density function (PDF) for a basic dual hop cooperative relay network with an arbitrary number of interferers over Rayleigh fading channels are derived. Two system models are considered: in the first system model, the interferers are only at the relay node; and in the second system model, interferers are both at the relay and the destination. This work is further extended to Nakagami-m faded interfering channels. Simulation results are presented on outage probability performance to verify the theoretical analysis