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991.
Ki Won Sung Chae Y. Lee Kwang Hyuk Yim Agnes Gravrand 《Wireless Personal Communications》2009,50(4):469-481
Traffic asymmetry between uplink and downlink is expected to be a remarkable 3G characteristic in cellular mobile multimedia
communications. CDMA system with TDD is a good solution to this traffic asymmetry. However, the level of traffic asymmetry
may be significantly different from a cell to another cell. To tackle this problem and to support the traffic hot spot, crossed
slots are examined. The use of crossed slots is restricted within a certain range of a cell by investigating the inter-cell
interference and the maximum planned load factor. We examine the radius of inner zone and discuss the capacity of downlink
crossed slots for various neighbor cell environments. Computational results show that the capacity increase in the target
cell is outstanding by reducing the service range of neighbor cells. When all six neighbors reduce their service range by
20%, the capacity at target cell crossed slot is increased by 35%. Monte Carlo simulation is performed with large scale fading
to verify the numerical analysis.
相似文献
Chae Y. LeeEmail: |
992.
Hassan Elhadidy Jan Franc Eduard Belas Pavel Hlídek Pavel Moravec Roman Grill Pavel Hoschl 《Journal of Electronic Materials》2008,37(9):1219-1224
Thermoelectric effect spectroscopy and photoluminescence techniques were used to study the defect levels in samples from three
crystals of CdTe:In grown by the vertical gradient freeze method. The main goal of the investigation was to study defects,
which strongly trap charge carriers or act as recombination centers in order to eliminate them from the technological process.
The main difference among detecting and non-detecting samples was the absence of electron traps with a very high capture cross-section
and energy 0.6 eV to 0.7 eV, which act as lifetime killers even at low concentrations. Recently published ab initio calculations show a complex of Te antisite and Cd vacancy within this energy range. 相似文献
993.
A Policy-based Approach for Reconfiguration Management and Enforcement in Autonomic Communication Systems 总被引:1,自引:0,他引:1
This paper presents an overview of the policy-based reconfiguration management and enforcement for autonomic communication
system platform (Pre-meacs). In contrast to existing management approaches, which require static priori policy configurations,
policies are created dynamically. The proposed Pre-meacs framework creates new policies at runtime in response to the changing
requirements. A hierarchical policy model is used to refine users and administrators’ high-level goals into low-level objectives.
The new approach ensures the success of the reconfiguration through monitoring feedback. The main components of Pre-meacs
framework for policy creation, storage, evaluation and enforcement are presented, and the procedures of Pre-meacs in networks
reconfiguration management are also demonstrated. Illustrative example demonstrates the performance of the proposed framework.
相似文献
Jie ChenEmail: |
994.
Ville Saari Jussi Mustola Jarkko Jussila Jussi Ryynänen Saska Lindfors Kari Halonen 《Analog Integrated Circuits and Signal Processing》2008,54(2):77-84
SiGe BiCMOS low-pass filter for a multicarrier WCDMA base-station receiver is described in this paper. The 4th-order Chebyshev
filter with a 0.1-dB passband ripple is designed to drive a high-resolution A/D converter. The −3-dB frequency of the implemented
filter can be programmed to four different bandwidths: 2.5, 5, 7.5, and 10 MHz depending on the number of received WCDMA channels.
The filter achieves +9.7-dBV in-band IIP3, +20-dBV out-of-band IIP3, and 8.5-nV/√Hz input-referred noise density with 10-MHz
bandwidth. The circuit uses a 2.5 V supply and has been fabricated in a 0.25-μm SiGe BiCMOS process. 相似文献
995.
Sensor nodes are densely deployed to accomplish various applications because of the inexpensive cost and small size. Depending
on different applications, the traffic in the wireless sensor networks may be mixed with time-sensitive packets and reliability-demanding
packets. Therefore, QoS routing is an important issue in wireless sensor networks. Our goal is to provide soft-QoS to different
packets as path information is not readily available in wireless networks. In this paper, we utilize the multiple paths between
the source and sink pairs for QoS provisioning. Unlike E2E QoS schemes, soft-QoS mapped into links on a path is provided based
on local link state information. By the estimation and approximation of path quality, traditional NP-complete QoS problem
can be transformed to a modest problem. The idea is to formulate the optimization problem as a probabilistic programming,
then based on some approximation technique, we convert it into a deterministic linear programming, which is much easier and
convenient to solve. More importantly, the resulting solution is also one to the original probabilistic programming. Simulation
results demonstrate the effectiveness of our approach.
This work was supported in part by the U.S. National Science Foundation under grant DBI-0529012, the National Science Foundation
Faculty Early Career Development Award under grant ANI-0093241 and the Office of Naval Research under Young Investigator Award
N000140210464.
Xiaoxia Huang received her BS and MS in the Electrical Engineering from Huazhong University of Science and Technology in 2000 and 2002,
respectively. She is completing her Ph.D. degree in the Department of Electrical and Computer Engineering at the University
of Florida. Her research interests include mobile computing, QoS and routing in wireless ad hoc networks and wireless sensor
networks.
Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D degree in
Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and
Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical
and Computer Engineering at University of Florida in May 2000 as an assistant professor, got an early promotion to an associate
professor with tenure in August 2003 and to a full professor in August 2005. He holds a University of Florida Research Foundation
(UFRF) Professorship from 2006 to 2009. He has published over 200 papers in refereed professional journals and conferences.
He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator
Award in 2002. He has served on several editorial boards of technical journals including IEEE Transactions on Communications,
IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also
been activitely participating in professional conference organizations such as serving as The Steering Committee Co-Chair
for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004,
and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007). 相似文献
996.
An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity. 相似文献
997.
An-xue Zhang Hui Wu Chen Guo Yan-sheng Jiang 《Journal of Infrared, Millimeter and Terahertz Waves》2008,29(10):946-952
For resolving the essential problem that the beam is too narrow in the application of the high-power UWB (Ultra-Wideband) antenna with single-source, a novel wide-beam high-power parabolic antenna with dual-source has been designed, and the edge of the paraboloid was cut in order to reduce the size of the antenna. Radiation properties of this proposed antenna are studied with finite-difference time-domain (FDTD) numerical method. The radiation properties of the proposed antenna can be improved by changing the structure of the parabolic antenna and adjusting the angle between the source and the axis of the antenna. The result shows that the beam-width has been improved significantly under the precondition of maintaining the peak power, and also the size of the antenna was minished by cutting the edge of the paraboloid. 相似文献
998.
Yee-Wen Yen H. W. Tseng K. Zeng S. J. Wang C. Y. Liu 《Journal of Electronic Materials》2009,38(11):2257-2263
The cross-interaction between Sn/Cu and Sn/Au interfacial reactions in an Au/Sn/Cu sandwich structure was studied. Field-emission
electron probe microanalysis (FE-EPMA) revealed that the Cu content in the three Au-Sn phases (AuSn, AuSn2, and AuSn4) was very low, less than 1 at.%. This means␣that Cu from the opposite Cu foil did not participate in the interfacial reaction
at the Sn/Au interface. On the opposite Sn/Cu side, Au-substituted (Cu,Au)6Sn5 formed within the initial 1 min of reflow. With prolonged reflow, the Au content in the Au-substituted (Cu,Au)6Sn5 increased and it transformed into a Cu-substituted (Au,Cu)Sn phase with 25 at.% Cu after 1 min of reflow at 250°C. The x-ray
diffraction (XRD) pattern confirmed the phase transformation of Au-substituted (Cu,Au)6Sn5 to Cu-substituted (Au,Cu)Sn phase. In addition, there was greater Au consumption in the Au/Sn/Cu sandwich joint structure
than in the single Au/Sn reaction case, due to some of the Au participating in the opposite Sn/Cu interfacial reaction. 相似文献
999.
Chuang Liu Dashuai Wang Peng Zhang Yanchen Qu 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(12):1433-1438
A compact and efficient mirror-less cavity is presented for an optically pumped 192-μm far-infrared laser. With a gold-coated mirror and 30°-inclined anti-reflection coated Ge plate serving as highly reflective mirrors, a folded mirror-less CH3F cavity is achieved. Maximum energy of 0.72 mJ is obtained with the pump energy of 600 mJ, which gives an energy increment of 75% in comparison with the previous 1.85-m mirror-less system. The beam divergence angle of the FIR radiation from this folded mirror-less cavity is measured to be 14.2 mrad. 相似文献
1000.
Wireless sensor networks (WSNs) are known to be highly energy-constrained and consequently lifetime is a critical metric in their design and implementation. Range assignment by adjusting the transmission powers of nodes create a energy-efficient topology for such networks while preserving other network issues, however, it may effect on the performance of other techniques such as network coding. This paper addresses the problem of lifetime optimization for WSNs where the network employs both range assignment and network-coding-based multicast. We formulate the problem and then reformulated it as convex optimization that offer a numerous theoretical or conceptual advantages. The proposed programming leads to efficient or distributed algorithms for solving the problem. Simulation results show that the proposed optimized mechanism decreases end-to-end delay and improve lifetime as compared by other conventional ones. 相似文献