Lowering customer’s switching cost using B2B services for telecommunication companies

A B2B transaction is a transaction between organizations. However, the ripple effects of a B2B transaction can reach the members of the organization and generate additional economic impact. Enterprise LTE (Long term evolution) is a newly introduced B2B service in the South Korean telecommunications market. While it provides secure and fast telecommunications services to businesses, it can also affect the employees’ utility in the business, since the service provider can provide a variety of additional services to employees who use the same telecommunications provider for their mobile devices. In this study, we empirically analyze how B2B and Enterprise LTE services affect consumer churn-in in the telecommunications market. We estimate consumer benefit based on the additional services provided after the introduction of the B2B service using conjoint analysis. We also estimate consumer switching cost for changing one’s mobile telecommunications service provider using contingent valuation method. By comparing these values, we analyze the switching probability of employees when B2B services are introduced at their workplace. The results show that in order to maximize revenue, considering the revenue gained from new subscribers and from fees for providing additional services, lowering service fees for additional services and maximizing market share are advisable.     

Dynamic programming approach to optimal vertex selection for polygon-based shape approximation

A new vertex selection scheme for polygon-based contour coders is presented. In the proposed method, final vertex points are determined by a 'two-step procedure'. In the first step, the initial vertices are simply selected from the contour, thereby constituting a subset of the original contour, using conventional methods such as the iterated refinement method (IRM) or progressive vertex selection (PVS) method. In the second step, a vertex adjustment process is incorporated to generate final vertices that are no longer confined to the contour and are optimal in view of the given distortion measure. For the optimality of the final vertices, a dynamic programming (DP)-based solution for the adjustment of the vertices is proposed. Consequently, the authors offer two main contributions. First, it is shown that DP can be successfully applied to vertex adjustment. Secondly, the use of DP enables global optimality to be achieved in vertex selection without any iterative processes. Experimental results are presented to demonstrate the superiority of the proposed method over traditional methods     

A novel hidden station detection mechanism in IEEE 802.11 WLAN

The popular IEEE 802.11 wireless local area network (WLAN) is based on a carrier sense multiple access with collision avoidance (CSMA/CA), where a station listens to the medium before transmission in order to avoid collision. If there exist stations which can not hear each other, i.e., hidden stations, the potential collision probability increases, thus dramatically degrading the network throughput. The RTS/CTS (request-to-send/clear-to-send) frame exchange is a solution for the hidden station problem, but the RTS/CTS exchange itself consumes the network resources by transmitting the control frames. In order to maximize the network throughput, we need to use the RTS/CTS exchange adaptively only when hidden stations exist in the network. In this letter, a simple but very effective hidden station detection mechanism is proposed. Once a station detects the hidden stations via the proposed detection mechanism, it can trigger the usage of the RTS/CTS exchange. The simulation results demonstrate that the proposed mechanism can provide the maximum system throughput performance.     

Uniaxial-process-induced strained-Si: extending the CMOS roadmap

This paper reviews the history of strained-silicon and the adoption of uniaxial-process-induced strain in nearly all high-performance 90-, 65-, and 45-nm logic technologies to date. A more complete data set of n- and p-channel MOSFET piezoresistance and strain-altered gate tunneling is presented along with new insight into the physical mechanisms responsible for hole mobility enhancement. Strained-Si hole mobility data are analyzed using six band k/spl middot/p calculations for stresses of technological importance: uniaxial longitudinal compressive and biaxial stress on [001] and [110] wafers. The calculations and experimental data show that low in-plane and large out-of-plane conductivity effective masses and a high density of states in the top band are all important for large hole mobility enhancement. This work suggests longitudinal compressive stress on [001] or [110] wafers and <110> channel direction offers the most favorable band structure for holes. The maximum Si inversion-layer hole mobility enhancement is estimated to be /spl sim/ 4 times higher for uniaxial stress on (100) wafer and /spl sim/ 2 times higher for biaxial stress on (100) wafer and for uniaxial stress on a [110] wafer.     

Adaptive processing using real weights based on a direct data domain least squares approach

In traditional, adaptive signal processing algorithms one change both the amplitude and phase of the weight vectors associated with an array at each of the antenna elements. The use of complex weights offers greater control over the array response at the expense of system complexity. However, it is easier if one requires only amplitude variation with a fixed phase for all the weight vectors associated with all the antenna elements. Because one uses only real arithmetic operations to find the amplitude of the weights connected to the antenna, the computational complexity is reduced considerably. Hence, this paper addresses the use of real weights in an adaptive system. In this paper we describe a new direct data domain least squares (D/sup 3/LS) method using real weights, which utilizes only a single snapshot of the data for adaptive processing. This technique may be useful for real time implementation of the D/sup 3/LS method on a chip.     

A learning approach of wafer temperature control in a rapid thermalprocessing system

This paper presents a learning approach for wafer temperature control in a rapid thermal processing system (RTP). RTP is very important for semiconductor processing system and requires an accurate trajectory following. Numerous studies have addressed this problem and most research on this problem requires exact knowledge of the system dynamics. The various approaches do not guarantee the desired performance in practical applications when there exist some modeling errors between the model and the actual system. In this paper, iterative learning control scheme is applied to RTP without exact information on the dynamics. The learning gain of the iterative learning law is estimated by neural networks instead of a mathematical model. In addition, the control information obtained by the iterative learning controller (ILC) is accumulated in the feedforward neuro controller (FNC) for generalization to various reference profiles. Through numerical simulations, it is demonstrated that the proposed method can achieve an accurate output tracking even without an exact RTP model. The output errors decrease rapidly through iterations when using the learning gain estimated and the FNC yields a reduced initial error, and so requires small iterations     

Ceramic chip antenna using meander conductor lines

A ceramic chip antenna using meander conductor lines has been designed, fabricated, and measured. The measured impedance bandwidth is 9.8% (1.85-2.06 GHz). It is increased to 19.1% (1.89-2.29 GHz) with an adjacent conducting plane. The radiation patterns are similar to that of a monopole antenna. The antenna gain is ~1.5 dBi     

Performance of 2-D RAKE receiver in a correlatedfrequency-selective Nakagami-fading

The bit error rate (BER) performance and the characteristics of a two-dimensional (2-D) RAKE receiver operating in a correlated frequency-selective Nakagami-fading environment are analyzed. Correlated fading between array elements whose fading statistics are identical across the same RAKE branch, as well as an arbitrary number of RAKE-branches with arbitrary finding statistics, are assumed. We derived an approximated signal-to-noise ratio (SNR) statistics for one RAKE branch with correlated multiple antennas, which is extended to that for multiple RAKE branches with arbitrary fading statistics, i.e., a 2-D RAKE receiver. The receiver's performance and characteristics are analyzed using the cumulative distribution function of the SNR at the 2-D RAKE receiver output and the BER under various conditions, Numerical results show that the improvement In performance of the 2-D RAKE receiver is brought about by the average SNR and diversity gains, which are identified by two parameters specifying the gamma distribution of SNR     

Dislocation scattering in n-GaN

The scattering of carriers due to dislocations is studied. Unlike semiconductors such as Si or GaAs, the major scattering mechanism for undoped or lightly doped samples is dislocation scattering instead of ionized impurity scattering. It was found that for GaN samples in the dislocation scattering region, the mobility is a function of the dislocation density and free carrier concentration, via a relationship. Temperature-variation mobility plots also indicate that a T^3/2 dependence component is present, which is also attributed to dislocation scattering.     

Fast Li+ Transport via Silica Network-Driven Nanochannels in Ionomer-in-Framework for Lithium Metal Batteries

For the development of all-solid-state lithium metal batteries (LMBs), a high-porous silica aerogel (SA)-reinforced single-Li⁺ conducting nanocomposite polymer electrolyte (NPE) is prepared via two-step selective functionalization. The mesoporous SA is introduced as a mechanical framework for NPE as well as a channel for fast lithium cation migration. Two types of monomers containing weak-binding imide anions and Li⁺ cations are synthesized and used to prepare NPEs, where these monomers are grafted in SA to produce SA-based NPEs (SANPEs) as ionomer-in-framework. This hybrid SANPE exhibits high ionic conductivities (≈10⁻³ S cm⁻¹), high modulus (≈10⁵ Pa), high lithium transference number (0.84), and wide electrochemical window (>4.8 V). The resultant SANPE in the lithium symmetric cell possesses long-term cyclic stability without short-circuiting over 800 h under 0.2 mA cm⁻². Furthermore, the LiFePO₄|SANPE|Li solid-state batteries present a high discharge capacity of 167 mAh g⁻¹ at 0.1 C, good rate capability up to 1 C, wide operating temperatures (from −10 to 40 °C), and a stable cycling performance with 97% capacity retention and 100% coulombic efficiency after 75 cycles at 1 C and 25 °C. The SANPE demonstrates a new design principle for solid-state electrolytes, allowing for a perfect complex between inorganic silica and organic polymer, for high-energy-density LMBs.