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191.
192.
Future wired-wireless multimedia networks require diverse quality-of-service (QoS) support. To this end, it is essential to
rely on QoS metrics pertinent to wireless links. In this paper, we develop a cross-layer model for adaptive wireless links,
which enables derivation of the desired QoS metrics analytically from the typical wireless parameters across the hardware-radio
layer, the physical layer and the data link layer. We illustrate the advantages of our model: generality, simplicity, scalability
and backward compatibility. Finally, we outline its applications to power control, TCP, UDP and bandwidth scheduling in wireless
networks.
The work by Q. Liu and G. B. Giannakis are prepared through collaborative participation in the Communications and Networks
Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative
Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes
notwithstanding any copyright notation thereon. The work by S. Zhou is supported by UConn Research Foundation internal grant
445157.
Qingwen Liu (S’04) received the B.S. degree in electrical engineering and information science in 2001, from the University of Science
and Technology of China (USTC). He received the M.S. degree in electrical engineering in 2003, from the University of Minnesota
(UMN). He currently pursues his Ph.D. degree in the Department of Electrical and Computer Engineering at the University of
Minnesota (UMN).
His research interests lie in the areas of communications, signal processing, and networking, with emphasis on cross-layer
analysis and design, quality of service support for multimedia applications over wired-wireless networks, and resource allocation.
Shengli Zhou (M’03) received the B.S. degree in 1995 and the M.Sc. degree in 1998, from the University of Science and Technology of China
(USTC), both in electrical engineering and information science. He received his Ph.D. degree in electrical engineering from
the University of Minnesota, 2002, and joined the Department of Electrical and Computer Engineering at the University of Connecticut,
2003.
His research interests lie in the areas of communications and signal processing, including channel estimation and equalization,
multi-user and multi-carrier communications, space time coding, adaptive modulation, and cross-layer designs. He serves as
an associate editor for IEEE Transactions on Wireless Communications since Feb. 2005.
G. B. Giannakis (Fellow’97) received his Diploma in Electrical Engineering from the National Technical University of Athens, Greece, 1981.
From September 1982 to July 1986 he was with the University of Southern California (USC), where he received his MSc. in Electrical
Engineering, 1983, MSc. in Mathematics, 1986, and Ph.D. in Electrical Engineering, 1986. After lecturing for one year at USC,
he joined the University of Virginia in 1987, where he became a professor of Electrical Engineering in 1997. Since 1999 he
has been a professor with the Department of Electrical and Computer Engineering at the University of Minnesota, where he now
holds an ADC Chair in Wireless Telecommunications.
His general interests span the areas of communications and signal processing, estimation and detection theory, time-series
analysis, and system identification -- subjects on which he has published more than 200 journal papers, 350 conference papers
and two edited books. Current research focuses on transmitter and receiver diversity techniques for single- and multi-user
fading communication channels, complex-field and space-time coding, multicarrier, ultra-wide band wireless communication systems,
cross-layer designs and sensor networks.
G. B. Giannakis is the (co-) recipient of six paper awards from the IEEE Signal Processing (SP) and Communications Societies
(1992, 1998, 2000, 2001, 2003, 2004). He also received the SP Society’s Technical Achievement Award in 2000. He served as
Editor in Chief for the IEEE SP Letters, as Associate Editor for the IEEE Trans. on Signal Proc. and the IEEE SP Letters, as secretary of the SP Conference Board, as member of the SP Publications Board, as member and vice-chair of the Statistical
Signal and Array Processing Technical Committee, as chair of the SP for Communications Technical Committee and as a member
of the IEEE Fellows Election Committee. He has also served as a member of the IEEE-SP Society’s Board of Governors, the Editorial
Board for the Proceedings of the IEEE and the steering committee of the IEEE Trans. on Wireless Communications. 相似文献
193.
运动估计算法是实时视频编解码技术的研究重点,高精度的匹配和补偿可以减少预测误差,提高视频图像的压缩效果.为降低在视频编码标准H.264中运动估计的高计算复杂度问题,提出了采用一种基于节点模型的可变形块匹配运动估计算法来搜索最佳运动矢量.该算法充分利用了H.264运动矢量的的统计特性和相关性,并采用基于像素差值分类的运动估计匹配准则.实验表明,在编码性能损失很小的条件下,该算法有效降低了视频压缩编码中运动估计的运算复杂度. 相似文献
194.
195.
Daniele Tarchi Romano Fantacci Cagri Tanriover Bahram Honary 《International Journal of Communication Systems》2009,22(4):483-501
One of the main challenges for future wireless systems is to enhance the effective data throughput by exploiting the allocated bandwidth as much as possible. Among several approaches at different layers, one of the most important is constituted by the so‐called link adaptation (LA) techniques. They are characterized by the adaptation of a set of transmission parameters to the channel state in order to improve performance. In this context, this paper is focused on the analysis of a particular class of LA techniques called adaptive modulation and coding, where the modulation and coding rate of transmission can vary according to the channel behavior. In particular, a novel LA algorithm, namely the timed window (TW) method, suitable for time‐division Duplex systems is proposed here. The performance of the TW algorithm is evaluated by taking actual user mobility conditions, communication channel behavior, as well as the physical layer effects into account. Finally, it is important to stress that, even if the wireless bearer considered in this study is TETRA (TErrestrial Trunked RAdio), the approach is quite general and it can be of interest for other wireless networks and can be optimized for different channel models (e.g. TU50, HT200, etc.). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
196.
This paper studies the cognitive broadcast channel in which the primary user com- municates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to communicate to two secondary receivers. Comparing with the existing cognitive radio channel which considers only one secondary receiver, cognitive broadcast channel studies the case that there are multiple secondary receivers. To this end, we investigate the fundamental limits of the performance of the Gaussian cognitive broadcast channel from the information theoretic perspective. Specifically, we derive the capacity region of the Gaussian cognitive degraded broadcast channel with weak interference. 相似文献
197.
This letter proposes a complexity reduction method to speed up the noiseless decoding of a bit-sliced arithmetic coding (BSAC) decoder. This scheme fully utilizes the group of consecutive arithmetic-coded symbols known as the decoding band and the significance tree structure sorted in order of significance at every decoding band. With the same audio quality, the proposed method reduces the number of calculations that are performed during the noiseless decoding in BSAC to about 22% of the amount of calculations with the conventional full-search method. 相似文献
198.
199.
Beni Yoshida 《Annals of Physics》2011,326(10):2566-2633
Recently, it has become apparent that the thermal stability of topologically ordered systems at finite temperature, as discussed in condensed matter physics, can be studied by addressing the feasibility of self-correcting quantum memory, as discussed in quantum information science. Here, with this correspondence in mind, we propose a model of quantum codes that may cover a large class of physically realizable quantum memory. The model is supported by a certain class of gapped spin Hamiltonians, called stabilizer Hamiltonians, with translation symmetries and a small number of ground states that does not grow with the system size. We show that the model does not work as self-correcting quantum memory due to a certain topological constraint on geometric shapes of its logical operators. This quantum coding theoretical result implies that systems covered or approximated by the model cannot have thermally stable topological order, meaning that systems cannot be stable against both thermal fluctuations and local perturbations simultaneously in two and three spatial dimensions. 相似文献
200.