SPICE compatible analytical electron mobility model for biaxial strained-Si-MOSFETs

This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain.Phonon scattering,columbic scattering and surface roughness scattering are included to analyze the full mobility model.Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made.The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor(MOS) devices.The results have also been compared with numerically reported results and show good agreement.     

NEST: novel eMBMS scheduling technique

In order to meet the growing demand for mobile multimedia broadcast services 3GPP includes evolved multimedia broadcast and multicast (eMBMS) services in LTE systems. The high data rates, low latency and QoS provisioning makes LTE systems more suitable for mobile broadcast and multicast services than legacy wireless networks. However, the 3GPP standards has not specified any scheduling strategy for this broadcast and multicast services. In this paper, we propose a novel eMBMS scheduling technique (NEST) which focuses on reducing the average waiting time (latency) of the broadcast services offered by LTE system. This paper has twofold contributions. We proffer NEST considering two types of impatience that is user equipment (UE) departure and UE request repetition. Our proposed scheduling strategy estimates the effects originating from the departure of the mobile UEs and UE request repetition case. It intelligently combines the advantages of both flat scheduling and on-demand scheduling in such a way that the overall latency of the system is reduced. We design a suitable modeling framework to analyze the performance of the system. Simulation experiments on typical LTE systems support the performance analysis and demonstrates 10 % gains while comparing with existing eMBMS scheduling available in present LTE systems.     

Anticipation of nitrided oxides electrical thickness based on XPS measurement

Plasma nitridation of thermally grown oxide films has proven to be an excellent gate dielectric in meeting the electrical requirements of the 65 nm node. As the 65 nm device performance is very sensitive to both physical thickness and nitrogen dose of these dielectric films, it is highly desirable to predict the electrical properties of such films. We present a simple physical model to forecast the capacitance-equivalent thickness (CET) of nMOS devices for 65 nm technology. The model is based on the total nitrogen dose and the dielectric physical thickness, both given by in-line X-ray photoelectron spectroscopy (XPS) measurement of the plasma nitrided gate dielectric. This model uses an estimated gate oxide dielectric constant, the gate depletion capacitance and the inversion layer capacitance. A good correlation is obtained between calculated and measured CET for plasma nitrided oxides from 19 to 30 Å CET and for a large range of incorporated nitrogen doses.     

Complexity reduction of digital filters using shift inclusive differential coefficients

We present a graph theoretical methodology that reduces the implementation complexity of the multiplication of a constant vector and a scalar. The complexity of implementation is defined as the required amount of computations like additions. The proposed approach is called minimally redundant parallel (MRP) optimization and is mainly presented in a finite impulse response (FIR) filtering framework to obtain a low-complexity multiplierless implementation. The key idea is to expand the design space using shift inclusive differential coefficients (SIDCs) together with computation reordering using a graph theoretic approach to obtain maximal computation sharing. The problem is formulated using a graph in which vertices and edges represent coefficients and computational cost (number of resources). The multiplierless solution is obtained by solving a set cover problem on the vertices in the graph. A simple polynomial run time algorithm based on a greedy approach is presented. The proposed approach is compared with common-subexpression elimination to show slightly better results and is combined with it for further reduction of complexity. Simulation results show that 50-60% complexity reduction is achieved by only applying the MRP algorithm, and 70% complexity reduction is obtainable by combining it with common-subexpression elimination under a delay constraint of two or three.     

Affective Learning — A Manifesto

The use of the computer as a model, metaphor, and modelling tool has tended to privilege the 'cognitive' over the 'affective' by engendering theories in which thinking and learning are viewed as information processing and affect is ignored or marginalised. In the last decade there has been an accelerated flow of findings in multiple disciplines supporting a view of affect as complexly intertwined with cognition in guiding rational behaviour, memory retrieval, decision-making, creativity, and more. It is time to redress the imbalance by developing theories and technologies in which affect and cognition are appropriately integrated with one another. This paper describes work in that direction at the MIT Media Lab and projects a large perspective of new research in which computer technology is used to redress the imbalance that was caused (or, at least, accentuated) by the computer itself.     

Subspace blind adaptive detection for multiuser CDMA

Direct adaptive realizations of the linear minimum mean-square error (MMSE) receiver for direct-sequence code-division multiple access possess the attractive feature of not requiring any explicit information of interference parameters such as timing, amplitudes, or spreading sequences; however, they need a training sequence for the desired user. Previously, a new blind adaptive receiver was proposed based on an anchored least mean-squared (LMS) algorithm that requires only the spreading code and symbol timing of the desired user but obviates the need for a training sequence. In this work, it is analytically demonstrated that the blind LMS algorithm always provides (nominally) faster convergence than the training driven LMS-MMSE receiver of but at the cost of increased tap-weight fluctuations or misadjustment. Second, the property that the optimal MMSE or minimum-output energy filter coefficients lies in the signal subspace is exploited to propose a new efficient blind adaptive receiver requiring fewer adaptive coefficients. Improved detector characteristics (superior convergence rates and steady-state signal-to-interference-plus-noise ratios) is indicated by analysis and supported by simulation     

Stochastic Modeling of TCP in Networks with Abrupt Delay Variations

An analytical model of TCP (Transport Control Protocol) over an end-to-end path with random abrupt round-trip time (RTT) changes is presented. Modeling the RTT as a stochastic process, we analytically quantify and compare between the degree of degradation of the steady-state average throughput and window size due to spurious retransmissions for the different versions of TCP (Reno/NewReno versus Tahoe). The modeling methodology in this paper is used for evaluating different design alternatives for TCP for highly dynamic networks.     

Stress-induced effects by the anodic oxide in ridge waveguide laserdiodes

This paper studies, both theoretically and experimentally, stress-induced effects on the lateral far-field behavior for ridge-type semiconductor laser diodes where anodic oxide is used for the definition of the stripe width. These effects consist of antiguiding under the stripe region, and of two positive waveguiding features near the stripe edges. For low-threshold devices, these effects may be more important than thermal effects, depending on the stress in the oxide. They put a lower limit on the built-in index guiding to be introduced by lateral etch outside the ridge region in order to maintain fundamental mode operation for wider stripes. The magnitude of these effects may be as large as Δn_ef=1×10^-3. An analytical mathematical model is deduced for computing stresses and strains for a certain ridge-shaped interface which bounds the elastic medium     

Charge, current, and noise partitioning in MOSFET in the presence of mobility degradation

The Ward-Dutton (WD) partitioning scheme is used extensively to develop transient and high-frequency advanced compact models in MOSFET analysis. However, it remains an open question if this scheme can be used for field-dependent mobility that is enhanced in state-of-the-art submicrometer technologies. In this paper, after demonstrating that the well-known WD partitioning is indeed invalid for field-dependent mobility, the authors develop a very general partitioning strategy that can always be defined in small-signal analysis for any arbitrary velocity-field relationship. It has also been shown that for large-signal operation, the existence of a partitioning scheme can be determined by the solution of an integral equation.