Laser induced boron doping of silicon is studied as a function of the laser pulse number and energy density, in a special configuration where the precursor gas (BCl3) is injected and chemisorbed on the Si surface prior to each laser pulse. In-situ optical diagnostics, based on the transient reflectivity at 675 nm, allow to control the evolution of the dopant concentration and of the doped layer thickness during the laser doping process. Samples are characterized by the four-point probe method, atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). As the laser pulse number is scanned from 10 to 200 at a constant laser pulse energy, the junction depth increases from 21 to 74 nm while its sheet resistance decreases from 220 to 17 Ω/. Moreover, boron concentrations well above the solubility limit (up to 31021 cm-3 for 200 pulses) and very abrupt box-like dopant profiles are obtained. So, laser doping, in this dopant gas injection configuration, seems to be a very attractive technique to meet the International Technology Roadmap for Semiconductors (ITRS) requirements for ultra-shallow junctions.

This paper addresses the fundamental challenges and possible solutions in designing and fabricating nanometer-scale CMOS transistor. Essential technology components such as advanced gate dielectrics, ultra-shallow junction, channel dopant profile engineering, and salicide are discussed. Ultra-scaled transistor with physical gate length down to 15 nm is demonstrated as a continued effort to push the traditional planar CMOS technology towards its physical limit.

This letter proposes a design methodology of a capacitor for a switched capacitor filter. The capacitor design method makes the capacitor accurate to the capacitance ratio and insensitive to the process deviation. The SCF designed is used for the PCM CODEC filter and the deviation of the frequency characteristic is below 0.05 dB for a process deviation 0.5 µm in 5 µm CMOS process.

Both macrodiversity and microdiversity can effectively overcome the harmful effect of fading. Much of previous work focused on their benefits to the reverse link in CDMA systems. However, their effects on the forward link are less well understood. In this paper, we analyze the CDMA forward-link capacity with macrodiversity and microdiversity. It is shown that macrodiversity causes forward-link capacity loss since the extra forward-link channels supported by the involved base stations enhance not only the received signal power, but also the total interference. Unfortunately the latter gains more whatever power allocation scheme is adopted. Based on the analysis of the cause of capacity loss, we further present a new transmission scheme, in which some joint control among the involved base stations is made to assure that the signals arrived at the desired mobile in phase and simultaneously. The simulation results show that in the new transmission scheme much higher capacity can be achieved with macrodiversity and the capacity increases rapidly with the number of involved base stations. A comparison of the forward-link capacity with microdiversity and macrodiversity indicates that both types of diversity can bring benefits to the forward-link capacity. However, with macrodiversity higher capacity can be obtained at the cost of complexity.

In this paper, we propose a synchronous reservation protocol that is efficient for supporting variable-sized messages in a wavelength division multiplexing (WDM)-based local network using a passive star topology. A control channel is used to coordinate message transmission on data channels. Time is slotted with fixed-sized slots. The network can accommodate a variable number of nodes and operate independently of the change in the number of nodes. Therefore, any "new" node can join the network anytime without network re-initialization. Moreover, with the protocol, we can avoid data channel and destination conflicts. We analyze the performance according to the variation of the end-to-end propagation delay with respect to one slot time, and validate the results by simulation.

The Task-Coalition Assignment Problem (TCAP) is a formalization of the distributed computation problem. In TCAP, a set of agents and a set of tasks are given. A subset of the agents processes a task to produce benefit. The goal of TCAP is to find the combination of the tasks and the subsets of the agents that maximizes the sum of the benefit. In this paper, we define 1-TCAP, which is a practical subclass of TCAP. In 1-TCAP, tasks and agents are characterized by scalar values. We propose a polynomial-time approximation algorithm for 1-TCAP, and show that this algorithm achieves an approximation ratio 9/4. Here, an algorithm achieves an approximation ratio α for a maximization problem if, for every instance, it produces a solution of value at least OPT/α, where OPT is the value of the optimal solution.

In this paper, we present an approximate analysis method for computing the call blocking probability and Erlang capacity of CDMA systems. The approximated results provide only a few percent difference from the exact values, while reducing the calculation complexity. For CDMA systems with 3 sectors, we also show that the system performances such as call blocking probability and Erlang capacity can be characterized just with two traffic parameters (the traffic load of the most loaded sector and the sum of traffic loads of the other remaining sectors) instead of three sector traffic loads especially when the required call blocking probability is given less than 2e-2, which makes the traffic engineers manage the system more easily.

This paper presents a historical review of fiber technologies from the 1970s till now, focused on design, transmission characteristics, and reliability assurance of silica optical fibers. Discussion is made by dividing the period into two phases; the first phase closing nearly at the end of the 1980s and the second one starting at the same time. As for the first phase, we present designs of graded-index multimode fiber and single-mode fiber, and development of dispersion shifted fiber. Mechanical reliability assurance and loss increase phenomena due to hydrogen are also described. Development of an optical fiber amplifier triggered the start of the second phase. Due to the introduction of WDM transmission systems as well as demand on high bit-rate transmission, fiber dispersion and nonlinearity have become indispensable factors to be taken into consideration for system design and performance evaluation. We discuss novel non-zero dispersion shifted fibers and dispersion compensating fibers, developed to meet the requirements for long distance and high bit-rate WDM transmission systems. Finally, discussions are made on the future research and development items, which are necessary to realize anticipating photonic networks.

This paper describes design optimization and performances of hybrid optical transmission lines consisting of effective-area-enlarged pure silica core fiber and dispersion compensating fiber. As a result of the design optimization, considering low nonlinearity and good bending characteristic, the developed fibers exhibit a span average loss of 0.208 dB/km, a span average dispersion slope of 0.02 ps/nm2/km and low nonlinearity with an equivalent effective area of 60 µm2. Further optimization of the relationship among the nonlinearity, the dispersion slope and the bending characteristic enables perfectly dispersion-flattened hybrid optical transmission lines exhibiting a low transmission loss of 0.211 dB/km, low nonlinearity with an equivalent effective area of 60 µm2 and small dispersion deviation of 0.03 ps/nm/km in a wavelength band wider than 40 nm.

We propose a new method that can speed up the modular multiplication by physically partitioning the key size into two slices. By using LSB-first and MSB-first approach on two respective partitioned hardware module in parallel, we reduce the number of iterations in modular multiplication from k to k/2+1 for k-bit operands, and the resulting performance is doubled when contrasted with an implementation purely by LSB-first or MSB-first approach.

In this paper, we study system-level diagnosis under the comparison approach proposed by Maeng and Malek. Sengupta and Dahbura designed an O(n5) time diagnosis algorithm for identifying all faulty nodes in general graphs (n is the number of nodes in a system). We consider diagnosis on a butterfly network BF(k,r) and propose O(k2 n) time diagnosis algorithms for locating all faulty nodes in BF(k,r).

This paper proposes a method for mapping a finite state machine (FSM) into a two-dimensional array of LUTs, which is a part of our plastic cell architecture (PCA). LSIs based on the PCA have already implemented as asynchronous devices. Functions that run on the LSIs must also be asynchronous. In order to make good use of the LSIs, a system that translates functions into circuit information for the PCA is needed. We introduce a prototype system that maps an asynchronous FSM onto the PCA. First, a basic mapping method is considered, and then we create three methods to minimize circuit size. Some benchmark suites are synthesized to estimate their efficiency. Experimental results show that all the methods can map an asynchronous FSM onto the PCA and that the three methods can effectively reduce circuit size.

Existing MultiCode-CDMA MAC protocols perform only single dimensional access control either in the code or time domain. In this paper, we propose a MAC protocol, called SCTAC which can perform simultaneous code-time access control to achieve better system utilization. Also, SCTAC intends to provide service differentiation among different traffic classes. In order to simultaneously control access in both the code and time domain, SCTAC decouples the function of transmission ordering from the function of packing the scheduled transmissions in the resource space. As such, different transmission scheduling algorithms can be adopted without altering the MAC protocol. A water filling approach is used for efficient transmission packing where each of the scheduled transmissions is treated as a rectangular capsule with an arbitrary size and the resource space is viewed as a water container. In addition, SCTAC uses different request sending probabilities with an improved probability update algorithm to achieve service differentiation. Simulation results indicate that SCTAC is capable of providing different performances to different traffic classes. The results also confirm that SCTAC can achieve higher throughput compared to single dimensional access control protocols. Therefore, SCTAC is a better MAC protocol.

Integration of spot-size converters (SSCs) with semiconductor optical amplifiers (SOAs) that improves chip-fiber optical coupling is inevitable for realizing high performance SOA modules. In this paper SSCs that can be easily integrated with SOAs and have little influence on the polarization sensitivity have been studied. We found that polarization insensitive active width-tapered SSCs can be realized by an optimum waveguide design of tensile-strained bulk structures. The SOA module exhibited large fiber-to-fiber gain (> 19 dB), small polarization sensitivity (< 0.4 dB), high fiber-coupled saturation output power (> +11.7 dBm) and record low module noise figure (< 6.3 dB) for the signal wavelength range of 1530-1560 nm.

The main objective of vehicle suspensions is to improve ride comfort and road holding ability. Though passive suspensions consist of spring and damper, active suspensions adopt an actuator in addition to passive suspensions. In this paper, a quarter car model with an asymmetric hydraulic actuator is used. Moreover, the damping coefficient of the damper, which is changed according to the actuator velocity, is considered. The LPV (Linear Parameter Varying) model is obtained by applying feedback linearization technique. Next, a gain-scheduled controller, based on LQ regulator with different weighting factor, is designed according to the actuator velocity and the stability of the proposed controller is also proved. The effectiveness of the proposed controller is shown by numerical simulations.

A technique that uses a linear prediction error filter (LPEF) and an adaptive digital filter (ADF) to achieve noise reduction in a speech degraded by additive background noise is proposed. It is known that the coefficients of the LPEF converge such that the prediction error signal becomes white. Since a voiced speech can be represented as the stationary periodic signal over a short interval of time, most of voiced speech cannot be included in the prediction error signal of the LPEF. On the other hand, when the input signal of the LPEF is a background noise, the prediction error signal becomes white. Assuming that the background noise is represented as generate by exciting a linear system with a white noise, then we can reconstruct the background noise from the prediction error signal by estimating the transfer function of noise generation system. This estimation is performed by the ADF which is used as system identification. Noise reduction is achieved by subtracting the noise reconstructed by the ADF from the speech degraded by additive background noise.

We applied a Brillouin-OTDR, which is a distributed optical fiber strain sensor, to two actual concrete piles. The piles were made for use as highway foundations by on-site-pouring at construction sites and underwent load testing to ensure that their characteristics satisfied the required levels. Compressive strain caused by the load exerted on the piles was measured to an accuracy of 0.01% and a spatial resolution of 1 m. This measurement was obtained by embedding a strain-sensing optical fiber in the piles during construction. The results showed that there was good agreement between the measured strain and both the theoretical values and the values obtained with a conventional strain gauge based on electric resistance. Furthermore, the obtained strain distribution reflected the effects of friction between the pile surface and the ground. These results demonstrate the effectiveness of the Brillouin-OTDR for this kind of testing and also as a means of obtaining detailed data on the strain in concrete piles.

A digital circuit technique is proposed to process directly bit-stream signals from analog-to-digital converters based on sigma-delta modulation. Newly developed adder and multiplier are fundamental circuit modules for the processing. Using the fundamental modules and up/down counters, other circuit modules such as divider and square root circuits are also realized. The signal processors built of the modules have advantages over multi-bit Nyquist rate processors in circuit scale by the following two distinct features: First, single-bit/multi-bit converters are not needed at the inputs of the processors because the arithmetic modules directly process bit-stream signals. Secondly, the arithmetic modules consist of small number of logic gates. As an application of the technique to digital signal processing for communications, a QPSK demodulator is presented. The demodulator is structured with 40% of logic gates consumed by an equivalent multi-bit demodulator.

Due to large capacitance, high access ratio and wide access bitwidth, frame memory is one of the most energy consuming devices in modern video encoders. This paper proposes a new architectural technique to reduce energy dissipation of frame memory through adaptive bitwith compression. Unlike related approaches, the technique utilizes the fixed order of memory accesses and data correlation of video sequences, by dynamically adjusting the memory bitwidth to the number of bits changed per pixel. Instead of treating the data bits independently, we group the most significant bits together, activating the corresponding group of bit-lines adaptively to data variation. The approach is not restricted to the specific bit-patterns nor depends on the storage phase. It works equally well on read and write accesses, as well as during precharging. Simulations show that using this method we can reduce the total energy consumption of the frame memory cell array by 20% without affecting the picture quality. The implementation scheme is simple yet compact.

We propose a set of Fabry-Perot etalons integrated in a planar lightwave circuit (PLC-FPE) designed for a unified system for broadcasting and communication. A PLC-FPE containing four etalons having different cavity lengths is fabricated and their loss and frequency characteristics are investigated. The total loss and the maximum finesse were found to be 8 dB and 34, respectively.