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Effect of environment on the fatigue and the tensile properties of glass fiber reinforced vinyl ester and epoxy thermosets
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A learning approach for prioritized handoff channel allocation in mobile multimedia networks
Get PDFAn efficient channel allocation policy that prioritizes handoffs is an indispensable ingredient in future cellular networks in order to support multimedia traffic while ensuring quality of service requirements (QoS). In this paper we study the application of a reinforcement-learning algorithm to develop an alternative channel allocation scheme in mobile cellular networks that supports multiple heterogeneous traffic classes. The proposed scheme prioritizes handoff call requests over new calls and provides differentiated services for different traffic classes with diverse characteristics and quality of service requirements. Furthermore, it is asymptotically optimal, computationally inexpensive, model-free, and can adapt to changing traffic conditions. Simulations are provided to compare the effectiveness of the proposed algorithm with other known resource-sharing policies such as complete sharing and reservation policies
Performance Analysis of Bit-Interleaved Space-Time (BI-ST) Coded Systems Over Wireless Channels
Get PDFIn this paper a union bound on the bit error probability of bit-interleaved space-time (BI-ST) coded systems is derived. The derivation is based on the uniform interleaving assumption of the coded sequence prior to transmission over the multiple antennas. The performance of a BI-ST coded system is a function of how the bit errors are distributed over the signals in the codeword. In this paper, we derive this distribution as well as the corresponding pairwise error probability. The bound is a function of the distance spectrum of the code, the signal constellation used and the space-time (ST) encoding scheme. The bound is derived for a general BI-ST coded system and applied to two specific examples; namely, the BI space-time coded modulation (BI-STCM) and the BI space-time block codes (BI-STBC). Results show that the analysis provides a close approximation to the performance for a wide range of signal-to-noise ratios (SNR)
Synthesis of MVL Functions - Part I: The Genetic Algorithm Approach
Get PDFMultiple-Valued Logic (MVL) has been used in the design of a number of logic systems, including memory, multi-level data communication coding, and a number of special purpose digital processors. Several algorithms have been proposed in the literature for synthesis of multiple valued logic functions. None of these algorithms provides absolute optimum results for synthesis of these functions. The search space is too large to be explored by deterministic algorithms. In this paper, a Genetic Algorithm based algorithm for synthesis of MVL functions is proposed. The algorithm is tested using 200 randomly generated 2-variable 4-valued functions. The results obtained show that the introduced algorithm outperforms the deterministic technique based on the direct cover approach [3] in terms of the average number of product terms required to realize a given MVL function
Path-loss and time dispersion parameters for indoor UWB propagation
Get PDFThe propagation of ultra wideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of the UWB technology and its applications. The objective of this work is to obtain a better assessment of the potentials of UWB indoor communications by characterizing the UWB indoor communication channels. Channel characterization refers to extracting the channel parameters from measured data. An indoor UWB measurement campaign is undertaken. Time-domain indoor propagation measurements using pulses with less than 100 ps width are carried out. Typical indoor scenarios, including line-of-sight (LOS), non-line-of-sight (NLOS), room-to-room, within-the-room, and hallways, are considered. Results for indoor propagation measurements are presented for local power delay profiles (local PDP) and small-scale averaged power delay profiles (SSA-PDP). Site-specific trends and general observations are discussed. The results for path-loss exponent and time dispersion parameters are presented
A Novel Internal Model Control Scheme for Adaptive Tracking of Nonlinear Dynamic Plants
Get PDFAdaptive tracking of nonlinear dynamic plants is presently an active area of research. The design of on-line nonlinear controller for tracking of nonlinear plants has always been an inevitable computationally complex procedure. In this paper a novel method to facilitate controller design for output tracking of wide range of nonlinear plants based on a new control oriented model known as U-model is presented. The use of U-model alleviates the computational complexity of on-line nonlinear controller design that arises when using other modelling frame works such as NARMAX model. The U-model utilizes only past data for plant modelling and standard root solving algorithm for control law formulation. The control structure of the scheme contains two feedback loops. The innerloop, where inverse of the plant is developed based on adaptive U-model. Outer-loop, which is designed using linear control theory to improve tracking and disturbance rejection properties of the overall system. The effectiveness of the proposed scheme is illustrated by simulating a nonlinear plant and by real-time speed control of a laboratory scale DC moto
"A CMOS analog cell and its applications in analog signal processing"
Get PDFThis paper presents a core cell that can be reconfigured and combined with current mirrors to implement exponential, logarithmic, multiplier, divider and raise-to-power function circuits. The proposed circuit uses CMOS transistors operating in the strong inversion. The proposed circuits has been verified with the 0.8µm CMOS technology by HSPICE simulations. The simulations results confirm the functionality of the proposed circuits. The proposed circuits paves the way for designing analog signal processors