Interference Mitigation Using Uplink Power Control in 5G Relay-Based Heterogeneous Networks

Heterogeneous network (HetNet) is an attractive solution for future cellular networks with high data rate and coverage requirements. In HetNets, small cells such as micro cells, pico cells, femto cells and relay node (RN) are added to the network of macro cells in the same region. A large number of low power RNs produces new cell edges with significant intra-cell and inter-cell interferences. In the uplink (UL) scenarios of time-division based HetNets with RN, the user equipment (UE) desired signal may be interfered by the transmissions of the co-channel UEs during the first time slot and by the transmissions of the co-channel UEs or RNs during the second time slot. The interference caused by the RNs may significantly degrade the UE signal. UL transmission power control (PC) is essential for mitigating interference and, as a result, enhancing the cell edge and overall system performance. This research proposes a PC algorithm in order to mitigate the UL interference in 5g relay-based HetNets. This research also investigates the UL performance of HetNets when PC is applied at the RNs. Simulation results indicate that UL PC at the RNs greatly reduces average interference and improves average UL signal-to-interference-plus-noise ratio (SINR) and average UL end-to-end throughput compared to the situation in which UL PC is not implemente

Functional significance of the hemadsorption activity of influenza virus neuraminidase and its alteration in pandemic viruses

Human influenza viruses derive their genes from avian viruses. The neuraminidase (NA) of the avian viruses has, in addition to the catalytic site, a separate sialic acid binding site (hemadsorption site) that is not present in human viruses. The biological significance of the NA hemadsorption activity in avian influenza viruses remained elusive. A sequence database analysis revealed that the NAs of the majority of human H2N2 viruses isolated during the influenza pandemic of 1957 differ from their putative avian precursor by amino acid substitutions in the hemadsorption site. We found that the NA of a representative pandemic virus A/Singapore/1/57 (H2N2) lacks hemadsorption activity and that a single reversion to the avian-virus-like sequence (N367S) restores hemadsorption. Using this hemadsorption-positive NA, we generated three NA variants with substitutions S370L, N400S and W403R that have been found in the hemadsorption site of human H2N2 viruses. Each substitution abolished hemadsorption activity. Although, there was no correlation between hemadsorption activity of the NA variants and their enzymatic activity with respect to monovalent substrates, all four hemadsorption-negative NAs desialylated macromolecular substrates significantly slower than did the hemadsorption-positive counterpart. The NA of the 1918 pandemic virus A/Brevig Mission/1/18 (H1N1) also differed from avian N1 NAs by reduced hemadsorption activity and less efficient hydrolysis of macromolecular substrates. Our data indicate that the hemadsorption site serves to enhance the catalytic efficiency of NA and they suggest that, in addition to changes in the receptor-binding specificity of the hemagglutinin, alterations of the NA are needed for the emergence of pandemic influenza viruses

Substituent effects in hydroxyiodination of 1,2-diacyloxycyclohex-3-enes

The reaction of 1,2-diacyloxycyclohex-3-enes with iodinating agents in the presence of water has been investigated. The process is inherently diastereoselective, with many reactions giving only two of the four possible diastereoisomers which could be obtained. However, the regiocontrol is variable: highest selectivities are observed when pivalates are present on the periphery of the cycloalkene, when single regio- and diastereoisomers are obtained from the reactions. (c) 2006 Elsevier Ltd. All rights reserved

Asymmetric aziridine synthesis by aza-Darzens reaction of N-diphenylphosphinylimines with chiral enolates. Part 1: formation of cis-aziridines

Theaza-Darzens ('ADZ') reactions off-diphenylphosphinyl (W-Dpp') imines with chiral enolates derived from oxazolidinones and camphorsultam have been Studied. Whilst oxazolidinone enolates reacted poorly in terms of aziridination, the use of the chiral enolate derived from both antipodes of N-bromoacetyl 2, 10-camphorsultam, 2R-(5) and 2S-(5), with N-diphehenylphosphinyl aryl and tert-butylimines proceeded in generally good yield to give, respectively, (2'R,3'R)- or (2'S,3'S)-cis-N-diphenylphosphinyl aziridinoyl sultams of high de. (c) 2006 Elsevier Ltd. All rights reserved

Asymmetric aziridine synthesis by aza-Darzens reaction of N-diphenylphosphinylimines with chiral enolates. Part 2: inversion of diastereoselectivity

The aza-Darzens ('ADZ') reactions of N-diphenylphosphinyl ('N-Dpp') imines with chiral enolates derived from N-bromoacetyl 2S-2,10-camphorsultam proceed in generally good yield to give N-diphenylphosphinyl aziridinoyl sultams. However, the stereoselectivity of the reaction is dependent upon the structure of the imine substituent: when the chiral enolate was reacted with arylimines substituted in the ortho-position, mixtures of cis- and trans-2'R,3'R-aziridines were obtained, often with a complete selectivity in favour of the trans-isomer. (c) 2006 Elsevier Ltd. All rights reserved

Performance of Hard Handover in 5G Heterogeneous Networks

To satisfy the high data demands in future cellular networks, an ultra-densification approach is introduced to shrink the coverage of base station (BS) and improve the frequency reuse. In an ultra-densification approach, small cells such as relay node (RN), micro, pico and femto base stations (BSs) are deployed to the network of macro cells in the same geographic region, forming HetNet. HetNets introduce some notable challenges like inter-cell-interference-coordination (ICIC), mobility management and backhaul provisioning. In this paper, we investigate the performance of the hard handover (HHO) in 5G HetNets. The performance metrics are the total number of handovers and the outage probability. Simulation results show that the average outage probability is decreased in HetNet scenario compared the macro only scenario. However, this improvement comes at the expense of increase number of handover

Hydroxyselanylation of acyloxycyclohex-3-enes

In contrast to the corresponding hydroxyiodination reactions, the reaction of acetoxycyclohex-2-ene 1 with N-PSP in the presence of water shows little regiocontrol, but is highly diastereoselective. However, the same reaction of the (R)-phenylglycinate derivative of (+/-)-cyclohexen-3-ol is highly diastereoselective, and regioselective. A hydrogen-bonding interaction is proposed to rationalize these differing selectivities. (c) 2007 Published by Elsevier Ltd