Effect Of Channel Interference Research Articles

Concurrent Direct Inter-ONU and Upstream Communications in IMDD PONs Incorporating P2MP Flexible Optical Transceivers and Advanced Passive Remote Nodes

Driven by a large number of emerging diversified services, in the 5G and beyond era, concurrent direct inter-ONU and upstream communications inside a PON-based mobile access network are highly desirable to provide dynamic, ultra-dense, and fast ONU-to-ONU (without involving an OLT) and ONU-to-OLT connections. To cost-effectively deliver highly dynamic and low latency direct inter-ONU communications, this paper proposes and experimentally demonstrates novel concurrent direct inter-ONU and upstream communications in an upstream 27 km, >62.47 Gbit/s IMDD PON. For supporting inter-ONU communications between a large number of ONUs, an advanced passive remote node is also proposed. Based on different passive optical components, this remote node can be implemented using two approaches, which can, respectively, reduce the inter-ONU signal power losses by >12.2 dB and >16.6 dB (for 128 ONUs) in comparison with existing inter-ONU communication techniques’ remote nodes. In each ONU and OLT, a single pair of cascaded IFFT/FFT-based point-to-multipoint (P2MP) flexible optical transceivers are employed to simultaneously and dynamically establish multiple ONU-to-ONU and ONU-to-OLT communications according to actual users’ requirements. Experimental results show that the proposed network has excellent robustness against various transmission system impairments, including chromatic dispersion, the Rayleigh and Brillouin backscattering effects, and the channel interference effects. For each ONU, dynamic channel allocation can be made without compromising its overall performance.

Double-humped barrier effects in the R-matrix for fitting of fissile isotope

The Reich--Moore approach has been extensively used in the resolved resonance energy range (RRR) for a wide range of isotopes. The approximation was suggested for cross-section representation of fissile isotopes since experimental fission width distribution according to given resonance spin and parity showed that only a few degrees of freedom (DoF) was involved during the fission process. Experimental cross-section data in RRR were successfully reproduced, and the interference in fission channels were well described. The fitting of the fission cross-section data was done according to one or two fission channels for a given resonance spin (J) and parity (π). Using the two-fission channel representation, channel interference effects observed on cross-section data for fissile heavy isotopes were adequately treated but only on a phenomenological basis. Indeed, this approach is physically unsatisfactory since no fission penetrability is involved in reduced fission channel width evaluation, and therefore no actual connection between R-matrix fission channel widths and Aage Bohr transition fission channels can be made neither in terms of individual barrier height or by the shape. This paper intends to address model deficiency by including ‘fluctuating’ fission barrier penetrability as a function of resonance spin and parity.

Modification over Dithered DPLL to reduce the effect of narrowband channel interference

Digital signal processing based digital phase locked loop (DSP DPLL) are most commonly used for carrier phase tracking in the recent times. Phase locked loop (PLL) behaves in nonlinear fashion at the time of signal acquisition. The linearity is restored in the PLL behavior once acquisition is over and signal tracking is taking place. But the same PLL or DSP-DPLL shows non-linearity both during acquisition and tracking when narrowband channel interference is present in the received signal. In this paper, a single tone signal is introduced as channel interference to study the effect on DPLL and its modified versions. To overcome the effect of channel interference, a single tone dither signal is included in the loop of DPLL. Although an improvement in acquisition and tracking performance is observed, but addition of dither signal contributes to the phase error variance and consequently output noise to increase. Therefore, a further modification is proposed by incorporating an additional phase control in the digital control oscillator (DCO) of the loop to improve the output SNR. The proposed loop is implemented on reconfigurable logic platform using System Generator, a tool from Xilinx used to design real time DSP application. The hardware simulation results demonstrate a comparison among traditional DPLL, dithered DPLL and phase controlled dithered DPLL where the proposed version of the loop outperforms others in terms of acquisition and noise rejection. Keywords DSP Digital Phase Locked Loop, Phase Controlled DPLL, Channel Interference, Dither DPLL, VHDL System Design, Modified DCO

Performance of Dynamic Priority Based Interference Aware Channel Allocation in Wireless Mesh Networks for Energy Conservation

The Dynamic Wireless Mesh Network (DWMN) infrastructure is a pair or multiple dynamic nodes with networking capability to communicate with one another utilising Sink Nodes (SN). Due to its mobile nature, it is termed as Dynamic in nature. SN traverses over the predefined path over the Wireless Mesh Network. As the nodes engage into mobility, the neighbourhood table should be updated at a minimum rate of once every five seconds. The alarming fact in WMN is, Energy to transmit a bit is equivalent to computing hundreds of instructions at that instant. Hence there is a need to concentrate on energy dimension of DWMN. A node loses certain amount of energy while transmitting and receiving the packet, hence there is a minor decline in the initial energy of the node. The existing value of energy at a moment after transmitting and receiving the packet is coined as Residual Energy. The energy consumed by the node for transmitting and receiving the packet over the particular time frame is coined as Average Energy. Network Simulator v.2 tool has been utilised to simulate network creation with multiple mobile nodes for packet transmission or reception and packet drop conditions due to interference. Bandwidth Reservation (BR) for energy analysis is done by both Priority Based Interference Aware Bandwidth Reservation (PBIABR) and Interference Aware Bandwidth Reservation (IABR) for many flowing rates under dynamic scenario. Channel Priority plays a vital role to opt the channel which posses less interference for efficient bandwidth reservation for PBIABR. The opted channel will have the minimal channel interference effect. IABR posses the controllability character for data flow to establish end-to-end communication over Multi-Radio Multi-Channel (MRMC) - Wireless Mesh Network. This research paper focuses on deep analysis of Residual Energy (joule) compared with Interval (sec) and Average Energy (joule) compared with Interval (sec) under dynamic scenario for multiple flow rates by implementing PBIABR and IABR criteria.

System Capacity Analysis for Ultra-Dense Multi-Tier Future Cellular Networks

Ultra-dense multi-tier cellular networks have recently drawn the attention of researchers due to their potential efficiency in dealing with high-data rate demands in upcoming 5G cellular networks. These networks consist of multi-tier base stations including micro base stations with very high-system capacity and short inter-site distances, overlooked by central macro base stations. In this way, network densification is achieved in the same area as that of traditional mobile networks, which offers much higher system capacity and bandwidth reuse. This paper utilizes a well-known analytical tool, stochastic geometry for modeling and analyzing interference in ultra-dense multi-tier cellular networks. Primarily, we have studied different factors affecting the system capacity including the network densification, cell load, and multi-tier interference. The role of the ergodic channel capacity is also discussed. Moreover, the effects of channel interference, system bandwidth, and the network densification on the spectral and energy efficiencies of the network are observed. Finally, the results show that the network densification and the cell load have a profound impact on system performance as well as spectral and energy efficiencies of the networks.

Functional connectivity of the PFC via partial correlation

Functional near-infrared spectroscopy (fNIRS) has been applied to study of brain oxygenation and metabolism. In this study, we aimed to investigate the partial correlation (PC) in fNIRS signals on functional connectivity in the prefrontal cortex (PFC) during a modified version of the color-word matching Stroop task. A continuous wave 16 channels near-infrared spectroscopy device (ARGES Cerebro, Hemosoft Inc., Turkey) was used to measure the changes in HbO2 and Hb concentrations from 12 healthy volunteers. Partial correlation (PC) values were computed for each stimulus condition. The results of ANOVA test (p<0.05) in HbO2 and Hb signals indicate the bilateral connections between two brain hemispheres. The partial correlation analysis, by removing the common effect of channel interference, offers a suitable measure to evaluate the performance of the prefrontal cortex. Also, the results of partial correlation showed that compared to Hb signal, HbO2 signal is more sensitive to brain activities. This study suggests that fNIRS is a valuable tool for demonstrating the relationship between cortical function in complex cognitive activities.

Chemical control of channel interference in two-photon absorption processes.

The two-photon absorption (TPA) process is the simplest and hence the most studied nonlinear optical phenomenon, and various aspects of this process have been explored in the past few decades, experimentally as well as theoretically. Previous investigations have shown that the two-photon (TP) activity of a molecular system can be tuned, and at present, performance-tailored TP active materials are easy to develop by monitoring factors such as length of conjugation, dimensionality of charge-transfer network, strength of donor-acceptor groups, polarity of solvents, self-aggregation, H-bonding, and micellar encapsulation to mention but a few. One of the most intriguing phenomena affecting the TP activity of a molecule is channel interference. The phrase "channel interference" implies that if the TP transition from one electronic state to another involves more than one optical pathway or channel, characterized by the corresponding transition dipole moment (TDM) vectors, the channels may interfere with each other depending upon the angles between the TDM vectors and hence can either increase (constructive interference) or decrease (destructive interference) the overall TP activity of a system to a significant extent. This phenomenon was first pointed out by Cronstrand, Luo, and Ågren [Chem. Phys. Lett. 2002, 352, 262-269] in two-dimensional systems (i.e., only involving two components of the transition moment vectors). For three-dimensional molecules, an extended version of this idea was required. In order to fill this gap, we developed a generalized model for describing and exploring channel interference, valid for systems of any dimensionality. We have in particular applied it to through-bond (TB) and through-space (TS) charge-transfer systems both in gas phase and in solvents with different polarities. In this Account, we will, in addition to briefly describing the concept of channel interference, discuss two key findings of our recent work: (1) how to control the channel interference by chemical means, and (2) the role of channel interference in the anomalous solvent dependence of certain TP chromophores. For example, we will show that simple structurally induced changes in certain dihedral angles of the well-known betaine dye (TB type) will help fine-tune the constructive channel interference and hence increase the overall TP activity of molecules with this general TP channel structure. Another intriguing result we will discuss is observed for a tweezer-trinitrofluorinone complex (TS type) where, on moving from polar to essentially nonpolar solvents, the nature of the channel interference switches from destructive to constructive, leading to a net abnormal solvent dependence of the TP activity of the system. The present Account highlights the usefulness of the channel interference effect and establishes it as a new and unique way of controlling the TP transition probability in different types of three-dimensional molecules.

A Study on Mobile Target Estimation Resolution using Effects of Model Errors and Sensitivity Analysis

The antenna pattern in this case has a main beam pointed in the desired signal direction, and has a null in the direction of the interference.The conventional antenna pattern concepts of beam width, side lobes, and main beams are not used, as the antenna weights are designed to achieve a set performance criterion such as maximization of the output SNR.A new direction of arrival estimation method using effects of model errors and sensitivity analysis is proposed. Two subspaces are used to form a signal space whose phase shift between the reference signal and its effects of model error signal. Through simulation, the performance showed that the proposed method leads to increased resolution and improved accuracy of DOA estimation relative to those achieved with existing method. Since a desired signal is obtained after interference rejection through correction effects of model error, the effect of channel interference on the estimation is significantly reduced.

Understanding the Effect of Channel Interference and RSSI in IEEE 802.11 PCF

With the increased popularity and deployment of WLANs, a major challenge is how to efficiently assign these available channels in order to optimize the network performance. In this paper, we design a testbed to analyze the effect of Channel Interference and RSSI in IEEE 802.11b PCF. We have observed that the performance of all hosts is subject to important signal fading and interference. We believe that the data collected by our experiments may be of interest to network designers who want to know the effective capabilities before their deployment.

A centralised Transmission Tree Scheduling algorithm for IEEE 802.16 mesh networks

Rapid advances in the mobile communications and wireless technology fields in recent decades have prompted a move away from traditional cable-and optical-based networks towards broadband wireless networks. The broadband wireless access of IEEE 802.16 protocol, therefore, introduces an important issue for bandwidth usage of Subscriber Stations (SSs) in Wireless Metropolitan Area Network. This paper proposes a centralised Transmission Tree Scheduling (nTTS) algorithm for IEEE 802.16 mesh networks. The proposed algorithm takes the effects of channel interference into account and is designed to improve both the Channel Utilisation Ratio (CUR) and the QoS performance of the mesh network.

Role of bound states in channel-interference of harmonic generation

We calculated the power spectra of harmonic generation for the one-electron system in 7 potential models with different quantities of bound states. It indicates that the increase of weakly bound states has little influence on the enhancement of harmonic intensity in the high-order region. Further research on the so-called channel-interference of harmonic generation is obtained, which shows that the channel-interference of harmonic generation exists for all potential models. Therefore, channel-interference maybe a ubiquitous phenomenon for one-electron system driven by bichromatic field, and the increase of bound states can augment the effect of channel-interference. Our calculations can provide some insight on the mechanism of channel-interference and harmonic generation.

The effect of electronic autoionization on vibrational branching ratio in (1 + 1')-photon resonance-enhanced multiphoton ionization of molecules: dependence on laser intensity

We have studied the laser intensity effect on the vibrational branching ratio (VBR) in -photon resonance-enhanced two-photon ionization of molecules, considering the electronic autoionization through the lowest autoionizing (AI) state of symmetry. In this ab initio calculation we have studied resonant two-photon transitions from the ground state to the doubly excited autoionizing state of symmetry as well as to the electronic continuum (:) of molecules via the resonant intermediate levels. Transitions to two different continuum energies (-0.4500 au and -0.5853 au) have been considered; the first one is 1.36 eV above the dissociation threshold (-0.50 au) of the ion and the second one is 0.048 eV above the vibrational level of the ion in the ground state . Parallel transitions through other intermediate near-resonant rovibrational levels v = 0-3 and 5-20 with the allowed values of total angular momentum j of the state have been included in the calculation. Besides the effect of interference of direct ionization with autoionization channels, we have considered here (i) the effects of mutual interference among parallel autoionization channels and that among parallel ionization channels via the near-resonant and resonant rovibrational levels of the state and (ii) the effect of the two-photon coupling between intermediate rovibrational levels via the autoionizing state and the continuum in order to study the laser intensity dependence of vibrational distribution of ions in the ground state. It has been shown that these two effects (channel interference effect and two-photon coupling effect) lead to non-Franck-Condon type VBR and the values differ from those obtained by considering the direct ionization channels alone. The laser intensity dependence of VBR is also different from that obtained by neglecting the autoionization channels. For transitions to two different continuum energies these effects become prominent at two different laser intensities. Furthermore, it has been found that the transitions through different intermediate resonant rotational levels of the state give rise to different vibrational branching ratios.

Measurement of the required cross-polar protection ratio in G-PAL TV FM satellite transmissions planning

A measurement campaign using live TV broadcast satellite signals and receiving commercial equipment has been carried out to study the required cross-polar protection ratio at the receiving antenna in satellite transmission planning. This experiment provides useful and realistic conclusions for the optimum spectrum allocation of TV channels in broadcasting satellite systems, as for example, the frequency offset required between cross-polar channels depending on the cross-polar rejection at the receiving antenna, for a certain grade of video signal impairment due to the cross-polar channel interference effects, and taken also into account the noise contribution on the signal.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Study of the required crosspolar protection ratio in G-PAL TV FM satellite transmissions planning

A study including simulation and a measurement campaign using live TV broadcast satellite signals and receiving commercial equipment has been carried out to investigate the required cross-polar protection ratio at the terrestrial receiving antenna for satellite transmission planning. This experiment provides useful and realistic results for efficient channel allocation in the spectrum band of broadcast satellite systems. Among them is the frequency offset required between cross-polar channels, depending on the cross-polar rejection at the receiving antenna, for a certain degree of video signal impairment due to the cross-polar channel interference effect, and taking into account the noise contribution to the signal. A worst case in frequency offset value, i.e., larger subjective impairment of the picture at equal carrier to noise ratio (CNR), has been detected around 5 MHz (near the chroma carrier in G-PAL system 4.43 MHz) only for high values of CNR. Different subjective degradation of the image due to cross-polar channel interference and noise has been observed, and their particular contributions to impairment have been evaluated. >

A simple mathematical model of co-channel and adjacent channel interference in land mobile radio

A simple mathematical model is used to predict co-channel and adjacent channel interference effects in land mobile radio, valid for flat urban terrain. Results obtained, although oversimplified compared with real-life mobile radio systems, yield insights into the properties of differing types of modulation.

A simple mathematical model of co-channel and adjacent channel interference in land mobile radio

A simple mathematical model is used to predict co-channel and adjacent channel interference effects in land mobile radio, valid for flat urban terrain. Results obtained, although oversimplified compared with real-life mobile radio systems, yield insights into the properties of differing types of modulation.

Selectivity Requirements to Eliminate Adjacent Channel Interference on Multi-Channel Catv Systems

TV receiver and transmitter characteristics required for the elimination of visible adjacent channel interference effects are discussed. The interference mechanisms involved are explained. Effects caused by the upper adjacent channel signal are different in nature from those of a lower adjacent channel signal. It can be shown that the suppression of upper channel interference needs little extra effort, if any, in the receiver, but calls for special care in designing the VSB filter response at the transmitter (or headend modulator). To eliminate interference from the lower adjacent channel, however, the receiver selectivity has to meet requirements which are more stringent than those for the upper adjacent channel.

Entrance channel interference effect in the neutron decay of 2+ analogue resonances

Abstract The angular distributions of the decay neutrons populating 1 2 − , 3 2 − and 1 2 − states of 91Nb and 95Tc resulting from the s- and d-wave proton induced Jπ = 2+ analogue resonances are investigated. The experimental angular distributions show the interference effect arising from the coherence between the partial waves involved in the resonance. The analysis of the observation shows that it is necessary and sufficient that the interference be between the s 1 2 and d 5 2 partial waves in the entrance channel. The ratios of the spectroscopic factors and the relative signs of the reduced width amplitudes for the s 1 2 and d 5 2 protons are deduced from the data. The ratios of the spectroscopic factors agree with the (d, p) results.