Faster Algorithms for Construction of Recovery Trees Enhancing QoP and QoS

Medard et al. proposed an elegant recovery scheme (known as the MFBG scheme) using red/blue recovery trees for multicast path protection against single link or node failures. Xue et al. extended the MFBG scheme and introduced the concept of quality of protection (QoP) as a metric for multifailure recovery capabilities of single failure recovery schemes. They also presented polynomial time algorithms to construct recovery trees with good QoP and quality of service (QoS). In this paper, we present faster algorithms for constructing recovery trees with good QoP and QoS performance. For QoP enhancement, our O(n + m) time algorithm has comparable performance with the previously best O(n²(n + m)) time algorithm, where n and m denote the number of nodes and the number of links in the network, respectively. For cost reduction, our O(n + m) time algorithms have comparable performance with the previously best O(n²(n + m)) time algorithms. For bottleneck bandwidth maximization, our O(m log n) time algorithms improve the previously best O(nm) time algorithms. Simulation results show that our algorithms significantly outperform previously known algorithms in terms of running time, with comparable QoP or QoS performance.     

Maximizing Cooperative Diversity Energy Gain for Wireless Networks

We are concerned with optimally grouping active mobile users in a two-user-based cooperative diversity system to maximize the cooperative diversity energy gain in a radio cell. The optimization problem is formulated as a non-bipartite weighted-matching problem in a static network setting. The weighted-matching problem can be solved using maximum weighted (MW) matching algorithm in polynomial time O(n³). To reduce the implementation and computational complexity, we develop a Worst-Link-First (WLF) matching algorithm, which gives the user with the worse channel condition and the higher energy consumption rate a higher priority to choose its partner. The computational complexity of the proposed WLF algorithm is O(n) while the achieved average energy gain is only slightly lower than that of the optimal maximum weighted- matching algorithm and similar to that of the 1/2-approximation Greedy matching algorithm (with computational complexity of O(n² log n)) for a static-user network. We further investigate the optimal matching problem in mobile networks. By intelligently applying user mobility information in the matching algorithm, high cooperative diversity energy gain with moderate overhead is possible. In mobile networks, the proposed WLF matching algorithm, being less complex than the MW and the Greedy matching algorithms, yields performance characteristics close to those of the MW matching algorithm and better than the Greedy matching algorithm.     

Split versions of the Levinson-like and Schur-like fast algorithmsfor solving block-slanted-Toeplitz systems of equations

In Joshi and Yagle (1998) the Fredholm equations of one-dimensional (1-D) inverse scattering and LLS estimation were transformed via the orthonormal wavelet transform into a series of symmetric “block-slanted-Toeplitz” (BST) systems of equations. Levinson-like and Schur-like fast algorithms were presented for solving the BST systems. Here, we present split versions of the Levinson-like and Schur-like fast algorithms. The significance of these split algorithms is as follows. Although the Levinson-like and Schur-like fast algorithms reduce the complexity of solving the BST systems from O(n³) to O(n²), there still exists an inherent redundancy in these algorithms in the case where the BST system matrices have centrosymmetric blocks. This situation arises when a symmetric wavelet basis function (like the Littlewood-Paley) is used in the problem transformation. This redundancy is exploited here to derive the split Levinson-like and split Schur-like fast algorithms. These split algorithms reduce the number of multiplications required at each iteration by a factor of two, as compared with the Levinson-like and Schur-like algorithms     

Testing complex couplings in multiport memories

In this paper, the effects of simultaneous write access on the fault modeling of multiport RAMs are investigated. New fault models representing more accurately the actual faults in such memories are then defined. Subsequently, a general algorithm that ensures the detection of all faults belonging to the new fault model is proposed. Unfortunately, the obtained algorithms are of O(n²) complexity which is not practical for real purposes. In order to reduce the complexity of the former test algorithm a topological approach has been developed. Finally, a BIST implementation of one of the proposed topological algorithms is presented     

基于Tile自组装模型的最大匹配问题算法研究

Tile自组装模型作为一种重要的DNA计算模型,在解决NP问题时展现出了巨大优势.文中针对现有最大匹配问题DNA计算算法实验操作复杂,错误率高的缺点,提出了一种基于Tile自组装模型的最大匹配问题新算法.算法所需的Tile分子种类为O(mn),所需生物操作数为O(1),计算时间为O(m),计算空间复杂度为O(mn)(其中m为边数,n为顶点数,且O(m)=O(n²)).与现有的最大匹配问题DNA计算算法相比,本算法不仅可靠性更好,而且更具可操作性.     

Efficient time slot assignment algorithms for TDM hierarchical andnonhierarchical switching systems

Two efficient time slot assignment algorithms, called the two-phase algorithm for the nonhierarchical and the three-phase algorithm for the hierarchical time-division multiplex (TDM) switching systems, are proposed. The simple idea behind these two algorithms is to schedule the traffic on the critical lines/trunks of a traffic matrix first. The time complexities of these two algorithms are found to be O(LN²) and O(LM²), where L is the frame length, N is the switch size, and M is the number of input/output users connected to a hierarchical TDM switch. Unlike conventional algorithms, they are fast, iterative and simple for hardware implementation. Since no backtracking is used, pipelined packet transmission and packet scheduling can be performed for reducing the scheduling complexity of a transmission matrix to O(N²) and O(M²), respectively. Extensive simulations reveal that the two proposed algorithms give close-to-optimal performance under various traffic conditions     

Low-complexity centralized joint power and admission control in cognitive radio networks

This letter introduces a centralized joint power and admission control algorithm for cognitive radio networks. Its novelty lies in the proposed admission metric. Unlike those in existing algorithms, our metric predetermines the admission order of N secondary users which intend to access the network. This allows us to search a group of admitted secondary users with the bisection method. The proposed algorithm is shown by simulation to achieve a comparable performance to existing algorithms, and the computational complexity is reduced from O(N³) to O(N² log₂ N).     

The Characteristics of New n-Type Polycrystalline Silicon Thin-Film Transistors Employing Alternating Magnetic-Field-Enhanced Rapid Thermal Annealing

We fabricated a new top-gate n-type depletion-mode polycrystalline silicon (poly-Si) thin-film transistor (TFT) employing alternating magnetic-field-enhanced rapid thermal annealing. An n⁺ amorphous silicon (n⁺ a-Si) layer was deposited to improve the contact resistance between the active Si and source/drain (S/D) metal. The proposed process was almost compatible with the widely used hydrogenated amorphous silicon (a-Si:H) TFT fabrication process. This new process offers better uniformity when compared to the conventional laser-crystallized poly-Si TFT process, because it involves nonlaser crystallization. The poly-Si TFT exhibited a threshold voltage (V_TH) of -7.99 V at a drain bias of 0.1 V, a field-effect mobility of 7.14 cm²/V ldr s, a subthreshold swing (S) of 0.68 V/dec, and an ON/OFF current ratio of 107. The diffused phosphorous ions (P⁺ ions) in the channel reduced the V_TH and increased the S value.     

Analytical models for n+-p+ double-gate SOIMOSFET's

Previously, we proposed n⁺-p⁺ double-gate SOI MOSFET's, which have n⁺ polysilicon for the back gate and p⁺ polysilicon for the front gate to enable adjustment of the threshold voltage, and demonstrated high speed operation. In this paper, we establish analytical models for this device, This transistor has two threshold voltages related to n⁺ and p⁺ polysilicon gates: V_th1 and V_th2, respectively. V _th1 is a function of the gate oxide thickness t_Ox and SOI thickness t_Si and is about 0.25 V when t_Ox/t_Si=5, while V_th2 is insensitive to t_Ox and t_Si and is about 1 V. We also derive models for conduction charge and drain current and verified their validity by numerical analysis. Furthermore, we establish a scaling theory unique to the device, and show how to design the device parameters with decreasing gate length. We show numerically that we can design sub 0.1 μm gate length devices with an an appropriate threshold voltage and an ideal subthreshold swing     

Effect of ion energy on hydrogen diffusion in n- and p-GaAs

The ion energy during electron cyclotron resonance (ECR) plasma hydrogenation is found to have a strong effect on both the effective diffusivity and solubility of hydrogen in n⁺ and p⁺ GaAs. For fixed plasma exposure conditions (30 min, 250°C) the diffusion depths for -150 V acceleration voltage are ~50 and ~100% larger, respectively, in p⁺- and n⁺-GaAs compared to 0 V acceleration voltage. The smaller incorporation depths at lower ion energy coincide with much larger peak hydrogen concentrations and higher apparent thermal stability of passivated dopants     

Filtering and frequency estimation using perturbation formulas

A new method for updating the SVD is introduced, based on perturbation formulas. The complexity of the method is O(n²). Applications are made to frequency estimation and filtering     

Low complexity affine MMSE detector for iterative detection-decoding MIMO OFDM systems

Iterative turbo processing between detection and decoding shows near-capacity performance on a multiple-antenna system. Combining iterative processing with optimum front-end detection is particularly challenging because the front-end maximum a posteriori (MAP) algorithm has a computational complexity that is exponential. Sub-optimum detector such as the soft interference cancellation linear minimum mean square error (SIC-LMMSE) detector with near front-end MAP performance has been proposed in the literature. The asymptotic computational complexity of SIC-LMMSE is O(n_t ²n_r + n_tn_r ³ + n_tM_c2^Mc) per detection-decoding cycle where n_t is number of transmit antenna, nr is number of receive antenna, and Mc is modulation size. A lower complexity detector is the hard interference cancellation LMMSE (HIC-LMMSE) detector. HIC-LMMSE has asymptotic complexity of O(n_t ²n_r + n_tM_c2^Mc) but suffers extra performance degradation. In this paper, two front-end detection algorithms are introduced that not only achieve asymptotic computational complexity of O(n_t ²n_r + n_tn_r ² [Gamma (beta) + 1] + n_tM_c2^Mc) where Gamma(beta) is a function with discrete output {-1, 2, 3, ...,n_t} and O(n_tM_c2^Mc) respectively. Simulation results demonstrate that the proposed low complexity detection algorithms offer exactly same performance as their full complexity counterpart in an iterative receiver while being computational more efficient.     

一种基于QoE量化评估的服务选择算法

针对如何为互联网用户从多个相同或相似的服务中进行选择的问题,提出了一种新的服务选择算法:基于QoE(Quality of Experience)量化评估的服务选择算法(A Service Selecting Algorithm Based on Quantified QoE Evaluation,ASSABQ).该算法基于一种层次化评分模型,从历史评分中学习获取用户偏好,根据多种评价因素计算每个可用服务的满意度,并选择满意度最高的服务给用户.与已知算法相比,ASSABQ算法的复杂度从O(n²)下降到O(n).仿真实验结果表明,在相同应用场景下,采用ASSABQ算法得到的用户满意度比已知算法提高约10%.     

Punchthrough transient voltage suppressor for low-voltageelectronics

Transient voltage suppressors for electronic circuits with power supply voltage of 3.3 V or lower are urgently needed but unavailable due to excessive leakage of low-voltage reversed p-n diodes. We analyzed several candidate device structures by using two-dimensional device simulation. Adopting the punchthrough mechanism in an n⁺p⁺p^-n⁺ structure rather than the traditional avalanche mechanism in a p⁺n⁺ structure, we can achieve low standoff voltage with excellent performances in low leakage current, low capacitance, and low clamping voltage. The new device appears to be satisfactory for protecting future electronic systems with power supply voltage at least down to 1.5 V     

DC characteristics of high-breakdown-voltage p-i-n diodes made by20-MeV Si implantation in InP:Fe

A vertical p-i-n diode is made for the first time in InP:Fe using megaelectronvolt energy ion implantation, A 20-MeV Si implantation and kiloelectronvolt energy Be/P coimplantation are used to obtain a buried n⁺ layer and a shallow p⁺ layer, respectively. The junction area of the device is 2.3×10^-5 cm² and the intrinsic region thickness is ≈3 μm. The device has a high breakdown voltage of 110 V, reverse leakage current of 0.1 mA/cm² at -80 V, off-state capacitance of 2.2 nF/cm² at -20 V, and a DC incremental forward resistance of 4 Ω at 40 mA     

Levinson-type algorithms for polynomial fitting and for Choleskyand Q factors of Hankel and Vandermonde matrices

This paper presents Levinson (1947)-type algorithms for (i) polynomial fitting (ii) obtaining a Q decomposition of Vandermonde matrices and a Cholesky factorization of Hankel matrices (iii) obtaining the inverse of Hankel matrices. The algorithm for the least-squares solution of Hankel systems of equations requires 3n²+9n+3 multiply and divide operation (MDO). The algorithm for obtaining an orthogonal representation of an (m×n) Vandermonde matrix X and computing the Cholesky factors F of Hankel matrices requires 5mn+n² +2n-3m MDO, and the algorithm for generating the inverse of Hankel matrices requires 3(n²+n-2)/2 MDO. Our algorithms have been tested by means of fitting of polynomials of various orders and Fortran versions of all subroutines are provided in the Appendix     

A measurement method of the injection dependence of theconductivity mobility in silicon

A new electrical method to measure the conductivity mobility as a function of the injection level is proposed in this paper. The measurement principle is based on the detection of the voltage drop appearing across a n⁺-n-n⁺ (p⁺-p-p⁺) structure when a current step is forced into it at a given injection level in the intermediate region. This is obtained by using a three-terminal test pattern consisting of p⁺ , n⁺ layers realized on top of a n-n⁺ (p-p ⁺) epitaxial wafer, where the p⁺-n-n⁺ (n⁺-p-p⁺) surface diode is forward biased to monitor the conductivity of the epilayer. The use of separate terminals for injection control and mobility measurement allows this technique to overcome some limitations presented by other electrical methods available in literature, Mobility values measured up to 2·10¹⁷ cm^-3 are in good agreement with those predicted by the Dorkel and Leturcq's model (1981)     

Verification of electron distributions in silicon by means of hotcarrier luminescence measurements

This paper investigates the use of hot carrier luminescence (HCL) measurements as a mean for the verification of carrier energy distribution functions in submicron silicon devices subject to high electric fields. To this purpose, physically-based two-dimensional (2-D) simulations of the spectral distribution of HCL are compared with extensive experimental data on special purpose n⁺/n/n⁺ test structures that demonstrate lateral field profiles similar to real MOSFETs without the obscuring effects of a gate electrode. Good agreement between measured and simulated data is observed over wide channel length, bias, and temperature ranges, thus providing for the first time a direct verification of simulated electron energy distributions in a MOSFET-like environment     

WSN低功耗低时延路径式协同计算方法

针对云计算应用于无线传感器网络(Wireless Sensor Network,WSN)时延敏感型业务时存在的高传输时延问题,提出了一种WSN低功耗低时延路径式协同计算方法.该方法基于一种云雾网络架构开展研究,该架构利用汇聚节点组成雾计算层;在数据传输过程中基于雾计算层的计算能力分步骤完成任务计算,降低任务处理时延;由...     

Electrical characterization of ultra-shallow junctions formed bydiffusion from a CoSi2 layer

Ultra-shallow p⁺/n and n⁺/p junctions were fabricated using a Silicide-As-Diffusion-Source (SADS) process and a low thermal budget (800-900°C). A thin layer (50 nm) of CoSi₂ was implanted with As or with BF₂ and subsequently annealed at different temperatures and times to form two ultra-shallow junctions with a distance between the silicide/silicon interface and the junction of 14 and 20 nm, respectively. These diodes were investigated by I-V and C-V measurements in the range of temperature between 80 and 500 K. The reverse leakage currents for the SADS diodes were as low as 9×10 ^-10 A/cm² for p⁺/n and 2.7×10^-9 A/cm² for n⁺/p, respectively. The temperature dependence of the reverse current in the p ⁺/n diode is characterized by a unique activation energy (1.1 eV) over all the investigated range, while in the n⁺/p diode an activation energy of about 0.42 eV is obtained at 330 K. The analysis of the forward characteristic of the diodes indicate that the p⁺ /n junctions have an ideal behavior, while the n⁺/p junctions have an ideality factor greater than one for all the temperature range of the measurements. TEM delineation results confirm that, in the case of As diffusion from CoSi₂, the junction depth is not uniform and in some regions a Schottky diode is observed in parallel to the n⁺/p junction. Finally, from the C-V measurements, an increase of the diodes area of about a factor two is measured, and it is associated with the silicide/silicon interface roughness