Earticle

Wireless mesh networks (WMNs) have been proposed for realizing their goals, such as throughput and full connectivity, in wireless networks. The interference between nodes in WMNs is a critical limiting factor. Understanding of interference needs to develop novel approaches, such as channel re-assignment, route selection, and fair scheduling. Actually, throughput of WMNs has degraded when reassigning channels due to the intra and inters interference. In this paper, we study the extent problem of interference, which spreads the trials of channel re-assignment toward neighbor mesh routers. In particular, the extent of interference causes additional throughput degradation when compared to a pair-wise interference to a small fraction of the links. This implies that the pair-wise interference measurements may be optimistic when used to drive protocols in wireless mesh networks. We newly define an analytical model, which is referred to as a ripple effect problem. The defined model is a formal model of interference to estimate the maximum rate at which flows can safely send traffic without overloading network. The proposed model can exemplify how protocols should take the extent of interference into account. The simulation results show that the proposed model can exactly evaluate the attempts of channel re-assignment occurred from mesh networks.

Speech enhancement is a long standing problem with various applications like telephone conversation and speech recognition. The corruption of speech due to presence of additive background noise causes severe difficulties in various communication environments. If the background noise is evolving more slowly than the speech, then the estimation of the noise during speech pauses is easier as compared to non stationary noise. If in case the Noise is varying rapidly then estimation is more difficult. This paper focuses on the class of single-channel noise reduction methods that are performed with frequency domain using short-time Fourier Transform (STFT). There are number of publications and implementations on noise reduction systems. But, there are still some issues in non- stationary noisy systems. This single-channel approach is more dominant and effective approach for practical systems. From last few years, algorithms have been proposed for this problem but most of them are worked on noisy signal in current frame. So in this paper we are trying to propose the new model using Wiener filter by using the concept of multi-frame approach with different window sizes and overlaps. The proposed method shows the results with its superiority.

Recently, as the down-scailing of field-effect transistor devices continues, Schottky-barrier field-effect transistors (SB-FETs) have attracted much attention as an alternative to conventional MOSFETs. SB-FETs have advantages over conventional devices, such as low parasitic source/drain resistance due to their metallic characteristics, low temperature processing for source/drain formation and physical scalability to the sub-10nm regime. The good scalability of SB-FETs is due to their metallic characteristics of source/drain, which leads to the low resistance and the atomically abrupt junctions at metal (silicide)-silicon interface. Nevertheless, some reports show that SB-FETs suffer from short channel effect (SCE) that would cause severe problems in the sub 20nm regime.[Ouyang et al. IEEE Trans. Electron Devices 53, 8, 1732 (2007)] Because source/drain barriers induce a depletion region, it is possible that the barriers are overlapped in short channel SB-FETs. In order to analyze the SCE of SB-FETs, we carried out systematic studies on the Schottky barrier overlapping in short channel SB-FETs using a SILVACO ATLAS numerical simulator. We have investigated the variation of surface channel band profiles depending on the doping, barrier height and the effective channel length using 2D simulation. Because the source/drain depletion regions start to be overlapped each other in the condition of the $L_{ch}$~80nm with $N_D{\sim}1\times10^{18}cm^{-3}$ and $\phi_{Bn}$ $\approx$ 0.6eV, the band profile varies as the decrease of effective channel length $L_{ch}$. With the $L_{ch}$~80nm as a starting point, the built-in potential of source/drain schottky contacts gradually decreases as the decrease of $L_{ch}$, then the conduction and valence band edges are consequently flattened at $L_{ch}$~5nm. These results may allow us to understand the performance related interdependent parameters in nanoscale SB-FETs such as channel length, the barrier height and channel doping.

In this paper we present a method of separating musical instrument sound sources from their monaural mixture, where we take the harmonic structure of music into account and use the sparseness and the overlapping NMF [1] to select representative spectral basis vectors which are used to reconstruct unmixed sound. A method of spectral basis selection is illustrated and experimental results with monaural mixture of voice/cello and trumpet/viola are shown to confirm the validity of our proposed method.