A second-order blind source separation method for bilinear mixtures

In this paper, we are interested in the problem of Blind Source Separation using a Second-order Statistics (SOS) method in order to separate autocorrelated and mutually independent sources mixed according to a bilinear (BL) model. In this context, we propose a new approach called Bilinear Second-order Blind Source Separation, which is an extension of linear SOS methods, devoted to separate sources present in BL mixtures. These sources, called extended sources, include the actual sources and their products. We first study the statistical properties of the different extended sources, in order to verify the assumption of identifiability when the actual sources are zero-mean and when they are not. Then, we present the different steps performed in order to estimate these actual centred sources and to extract the actual mixing parameters. The obtained results using artificial mixtures of synthetic and real sources confirm the effectiveness of the new proposed approach.     

A Survey on Traffic Management in Software-Defined Networks: Challenges,Effective Approaches,and Potential Measures

Software-defined networks (SDNs), as an emerging paradigm by separating the control plane from the data plane, increases flexibility and network utilization and reduces redundancy and operational cost. Traffic management of software-defined networks can be defined as network traffic monitoring and analyzing measures to improve network performance and quality of service metrics. Traffic management as an effective instrument for optimizing network traffic can offer the appropriate services according to network situation. Due to the inherent characteristics of SDN, special techniques are required to analyze, predict, and adapt the network traffic in order to achieve an efficient traffic management mechanism. This paper surveys traffic management techniques of SDN in four distinct categories including, routing, load balancing, congestion control, and flow control to cover the impressible issues. Moreover, the differences between SDN and traditional networks are analyzed in terms of traffic management necessities across the various groups to further determine the dimensions affecting research in this area. Furthermore, the available algorithms in each group and their role in traffic management are reviewed as well as the research challenges and future trends.

     

Derivation of low-power first-order low-pass,high-pass and all-pass filters

In this letter, a new voltage-mode (VM) configuration for providing low-power and simultaneous realization of first-order low-pass, high-pass and all-pass filters is presented. The output of the all-pass filter is taken differentially. The proposed circuit contains low number of components, i.e., only two NMOS transistors, a floating battery, a grounded capacitor and a floating resistor. Adding two NMOS transistors to the proposed circuit it is modified as an all-pass filter with a single-ended output. The main advantage of the presented circuits in comparison with other counterparts is their extremely low power dissipation. Moreover, the floating resistor can be replaced with an additional NMOS transistor in triode region to provide electronic tunability. Simulation results using SPICE program are given to demonstrate the performance of the proposed circuit.     

Novel Voltage-Mode All-Pass Filter Based on Using DVCCs

In this paper, a novel design for realizing a voltage-mode (VM) all-pass filter utilizing two differential voltage current conveyors (DVCCs) is proposed. Also, the suggested filter uses a canonical number of passive elements (one grounded capacitor and one resistor) without requiring any element matching condition. The proposed filter has high input and low output impedances, which make it suitable for cascading. The effects of the nonidealities of the DVCCs on the proposed design are investigated. As an application, a quadrature oscillator is designed using the proposed VM all-pass filter and an integrator. The proposed filter and oscillator circuits are simulated using the SPICE simulation program to confirm the theory.     

Real-time processing and compression of DNA microarray images.

In this paper, we present a pipeline architecture specifically designed to process and compress DNA microarray images. Many of the pixilated image generation methods produce one row of the image at a time. This property is fully exploited by the proposed pipeline that takes in one row of the produced image at each clock pulse and performs the necessary image processing steps on it. This will remove the present need for sluggish software routines that are considered a major bottleneck in the microarray technology. Moreover, two different structures are proposed for compressing DNA microarray images. The proposed architecture is proved to be highly modular, scalable, and suited for a standard cell VLSI implementation.     

Arbitrary dual-band unequal Wilkinson power divider based on negative refractive index transmission lines

This paper focused on the application of negative refractive index transmission line (NRI-TL) in dual-band unequal Wilkinson power divider (WPD) with controllable frequency and power dividing ratio. Theory and design procedure of the dual-band NRI-TL are presented in details. For demonstration, two dual-band unequal Wilkinson power dividers (WPDs) with power dividing ratio of 2 : 1 and operating frequencies of 0.9 and 1.8 GHz are designed, fabricated and tested. The first unequal divider is based on 2-stage NRI-TLs and the second one is based on 4-stage NRI-TLs. In addition, these two types of NRI-TLs are presented to demonstrate that by increasing the number of NRI-TL unit-cells the phase response of the NRI-TLs converge to the desired characteristic. The good agreement between measured and simulated results confirmed the design concept and derived closed-form design equations. Measurements show that the first divider has 18.37% and 21.86% relative bandwidths and the second one has 33.52% and 29.12% relative bandwidths at 0.9 and 1.8 GHz, respectively. The design concept of this paper can be extended to equal dual-band power dividers with arbitrary frequency ratio.     

Queue Analysis and Multiplexing of Heavy-tailed Traffic in Wireless Packet Data Networks

Recent research based on traffic measurements shows that Internet traffic flows have a fractal nature (i.e., self-similarity property), which causes an underestimation of network engineering parameters when using the conventional Poisson model. Preliminary field measurements demonstrate that packet data traffic in wireless communications also exhibits self-similarity. In this paper, we investigate the queuing behavior of self-similar traffic flows for data applications in a packet-switching single-server wireless network. The traffic is generated by an on–off source with heavy-tailed on periods and exponentially distributed off periods. We extend previous analysis of a relation among the asymptotic distribution of loss probability, traffic specifications, and transmission rate for a wireline system to a wireless system, taking into account wireless propagation channel characteristics. We also investigate the multiplexing of heavy-tailed traffic flows with a finite buffer for the downlink transmission of a wireless network. Computer simulation results demonstrate that assumptions made in the theoretical analysis are reasonable and the derived relationships are accurate.     

High output impedance current-mode lowpass,bandpass and highpass filters using current controlled conveyors

Three new current-mode second-order filter configurations which employ one or two current controlled conveyors (CCCIIs) and three passive elements are presented. Each proposed filter can realize one of the bandpass, lowpass or highpass responses all at high impedance outputs. The proposed filters offer current-control of pole angular frequency ω_o without disturbing the parameter ω_o /Q. No component matching is required and all the passive and active sensitivities are low. PSPICE simulation results are given to confirm the theoretical analysis.     

Simulation of interconnect inductive impact in the presence of process variations in 90 nm and beyond

The on-chip inductive impact on signal integrity has been a problem for designs in deep-submicrometer technologies. The inductive impact increases the clock skew, max timing, and noise of bus signals. In this letter, circuit simulations using silicon-validated macromodels show that there is a significant inductive impact on the signal max timing (/spl sim/ 10% pushout versus RC delay) and noise (/spl sim/2/spl times/RC noise). In nanometer technologies, process variations have become a concern. Results show that device and interconnect process variations add /spl sim/ 3% to the RLC max-timing impact. However, their impact on the RLC signal noise is not appreciable. Finally, inductive impact in 65- and 45-nm technologies is investigated, which indicates that the inductance impact will not diminish as technology scales.