Thu, 24 Jul 2008 23:17:29 BST CiteULike: dcastros Xu http://www.citeulike.org/user/dcastro/author/Xu CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/2923786 <i>Microwave Magazine, IEEE, Vol. 9, No. 1. (2008), pp. 89-100.</i><br /><br />Radio communications in the past century have relied primarily on nonlinear devices to modulate and demodulate signals for wireless transmissions. This article reviews initial laboratory results obtained with new radios using linear interferometers to modulate and demodulate ultra-wide-band (UWB) signals. Automotive and chip fabrication industries apply such interferometers in new commercial radios for UWB communications. New-Wave Radio RG Bosisio YY Zhao XY Xu S Abielmona E Moldovan YS Xu M Bozzi SO Tatu C Nerguizian JF Frigon C Caloz K Wu doi:10.1109/MMM.2007.910923 Microwave Magazine, IEEE, Vol. 9, No. 1. (2008), pp. 89-100. 2008-06-24T14:14:00-00:00 2008 Microwave Magazine, IEEE 9 1 89 100 radio uwb http://www.citeulike.org/user/dcastro/article/2877934 <i>Acoustics, Speech, and Signal Processing, 1993. ICASSP-93., 1993 IEEE International Conference on, Vol. 4 (1993), pp. 153-156 vol.4.</i><br /><br />The use antenna arrays in cellular code division multiple access mobile communications is studied. Techniques to localize each mobile within the cell and to generate tracking adaptive receive (and transmit) beams are addressed. The authors show that such enhancement of the CDMA system results in increased system capacity and improved robustness to power control errors. Preliminary simulation results are presented for capacity and robustness improvements for typical scenarios Performance of CDMA mobile communication systems using antenna arrays B Suard AF Naguib G Xu A Paulraj doi:10.1109/ICASSP.1993.319617 Acoustics, Speech, and Signal Processing, 1993. ICASSP-93., 1993 IEEE International Conference on, Vol. 4 (1993), pp. 153-156 vol.4. 2008-06-09T19:24:43-00:00 1993 Acoustics, Speech, and Signal Processing, 1993. ICASSP-93., 1993 IEEE International Conference on 4 153 156 vol.4 antenna array cdma mobile http://www.citeulike.org/user/dcastro/article/2588737 <i>Consumer Communications and Networking Conference, 2004. CCNC 2004. First IEEE (2004), pp. 352-356.</i><br /><br />We present a novel, adaptive subchannel allocation algorithm for the downlink channel of a multiuser, OFDM-based wireless home network. Since channel resources are not adaptively allocated in a traditional OFDM system, some of the users with fixed frequency channel allocation may experience deep fading in a frequency-selective multipath environment. This problem can be mitigated using an adaptive algorithm, which can be modeled as an optimization problem that allocates the proper number of subchannels to achieve maximum channel capacity. We employ the classical bipartite matching algorithm to achieve optimal OFDM subchannel allocation. Simulation results show that the total capacity increases remarkably, and that higher channel capacity is achieved when the number of users is increased. In a wireless environment, the reallocation overhead can be large. As such, we propose a hybrid method for subchannel allocation to support more users while reducing the reallocation overhead. We simulated the performance of the hybrid algorithm and compared it with the matching-only algorithm. An adaptive subchannel allocation algorithm for OFDM-based wireless home networks Jian Zhu Benny Bing Ye Li Jun Xu doi:10.1109/CCNC.2004.1286886 Consumer Communications and Networking Conference, 2004. CCNC 2004. First IEEE (2004), pp. 352-356. 2008-03-26T08:27:30-00:00 2004 Consumer Communications and Networking Conference, 2004. CCNC 2004. First IEEE 352 356 adaptive algorithm allocation ofdm subchannel wireless http://www.citeulike.org/user/dcastro/article/2431216 <i>Broadcasting, IEEE Transactions on, Vol. 48, No. 3. (2002), pp. 237-245.</i><br /><br />Techniques using Reed-Solomon (RS) codes to recover lost packets in digital video/audio broadcasting and packet switched network communications are reviewed. Usually, different RS codes and their corresponding encoders/decoders are designed and utilized to meet different requirements for different systems and applications. We incorporate these techniques into a variable RS code and present encoding and decoding algorithms suitable for the variable RS code. A mother RS code can be used to produce a variety of RS codes and the same encoder/decoder can be used for all the derivative codes, with adding/detecting zeros, removing some parity symbols and adding erasures. A VLSI implementation for erasure decoding of the variable RS code is described and the achievable performance is quantitatively analyzed. A typical example shows that the signal processing speed is up to 2.5 Gbits/second and the processing delay is less than one millisecond, when integrating the decoder on a single chip. Therefore, the proposed algorithm and the encoder/decoder can universally be utilized for different applications with various requirements, such as transmission data rate, packet length, packet loss protection capacity, as well as layered protection and adaptive redundancy protection in DVB/DAB, Internet and mobile Internet communications. Variable shortened-and-punctured Reed-Solomon codes for packet loss protection Youshi Xu Tingting Zhang doi:10.1109/TBC.2002.803706 Broadcasting, IEEE Transactions on, Vol. 48, No. 3. (2002), pp. 237-245. 2008-02-26T20:04:21-00:00 2002 Broadcasting, IEEE Transactions on 48 3 237 245 coding reedsolomon http://www.citeulike.org/user/dcastro/article/2421436 <i>Antennas and Propagation Society International Symposium 2006, IEEE (2006), pp. 1295-1298.</i><br /><br />Support vector machines are a good candidate for the solution of antenna array processing problems such as beamforming and the angle of arrival estimation, because these algorithms provide superior performance in generalization ability and computational complexity. In this work we introduce three new approaches for antenna array beamforming based on support vector machines. The first one is based on the use of the linear support vector regressor. The second algorithm uses a nonlinear multiregressor to find the parameters of a linear beamformer and the third is an implementation of a nonlinear beamformer using a nonlinear support vector machine. Comparisons with conventional beamforming strategies and simulation results are provided to demonstrate the advantages of the support vector machine approach. Antenna array processing for radar applications using support vector machines Nan Xu CG Christodoulou M Martinez-Ramon T Ozdemir doi:10.1109/APS.2006.1710781 Antennas and Propagation Society International Symposium 2006, IEEE (2006), pp. 1295-1298. 2008-02-24T13:26:32-00:00 2006 Antennas and Propagation Society International Symposium 2006, IEEE 1295 1298 antenna applications array processing radar svm http://www.citeulike.org/user/dcastro/article/2397693 <i>Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on, Vol. 4 (2002), pp. 1626-1630 vol.4.</i><br /><br />The paper presents a multiple-input-multiple-output (MIMO) channel modeling technique for link level and system level simulations. The classical approach of wave superposition is adopted to generate MIMO channels that are statistically consistent in delay, frequency and angle domains. The paper proposes an efficient way to generate four dimensional MIMO channel transfer matrices based on standard channel statistics such as power delay profile (PDP) and power azimuth spectrum (PAS). A wave-based wideband MIMO channel modeling technique H Xu D Chizhik H Huang R Valenzuela Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on, Vol. 4 (2002), pp. 1626-1630 vol.4. 2008-02-19T08:19:21-00:00 2002 Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on 4 1626 1630 vol.4 channel mimo model wideband http://www.citeulike.org/user/dcastro/article/2002737 <i>Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on], Vol. 48, No. 4. (2000), pp. 988-1001.</i><br /><br />In CDMA systems with long codes, the users' signatures change in each bit period, impeding the estimation of the time-invariant multipath parameters. In this paper, correlation-matching methods are employed to blindly estimate those multipath parameters. For given code sequences, the output correlation matrix (parameterized by the unknown channel coefficients) is compared with its instantaneous approximation. By minimizing the Frobenius norm of the resulting error matrix, the channel parameters can be estimated up to a complex scalar ambiguity. Both batch and adaptive algorithms are derived. Under the assumption of i.i.d. code sequences, identifiability up to a complex scalar ambiguity for each channel is guaranteed, and the asymptotic convergence of the proposed algorithm is established. Furthermore, step-size selection for the adaptive version is investigated. When only the code sequence of the user of interest is available, a single user receiver is also derived. Simulation results verify those claims and provide comparisons with other methods Blind channel estimation for long code multiuser CDMA systems Zhengyuan Xu MK Tsatsanis doi:10.1109/78.827533 Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on], Vol. 48, No. 4. (2000), pp. 988-1001. 2007-11-28T10:24:25-00:00 2000 Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on] 48 4 988 1001 blind cdma channel estimation system http://www.citeulike.org/user/dcastro/article/1026604 <i>Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings, Vol. 1 (2005), 3 pp..</i><br /><br />This paper presents an efficient symbol timing synchronization algorithm for an orthogonal frequency division multiplexing (OFDM) system that is adapted to IEEE 802.16d standard. This efficient algorithm is based on the preamble structure defined in IEEE 802.16d. The preamble's symmetrical structure is exploited to reduce computational complexity. The useful signal can be distinguished from others according to the receipt of the long preamble, and the beginning of the signals can be found. The results of simulation show that the timing will be more accurate at very low signal-to-noise ratios. An efficient timing synchronization scheme for OFDM systems in IEEE 802.16d Jie-Ping Xu Bo-Ran Guan doi:10.1109/APMC.2005.1606206 Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings, Vol. 1 (2005), 3 pp.. 2007-01-05T12:20:36-00:00 2005 Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings 1 3 pp. 80216 ofdm synchronization time http://www.citeulike.org/user/dcastro/article/1867141 <i>Neural Networks and Signal Processing, 2003. Proceedings of the 2003 International Conference on, Vol. 1 (2003), pp. 663-666 Vol.1.</i><br /><br />Design strategies of pilot patterns based on two-dimension sampling theory for OFDM wireless system in highly frequency selective Rayleigh fading channel have been analyzed. The analysis and simulation results show that hexagonal pattern is the optimal pilot pattern for OFDM system based on two-dimension sampling theory. Optimal pilot patterns for OFDM system based on two-dimension sampling theory Binfeng Bai Xin Xu Yueming Cai Zi Ii Neural Networks and Signal Processing, 2003. Proceedings of the 2003 International Conference on, Vol. 1 (2003), pp. 663-666 Vol.1. 2007-11-05T10:27:55-00:00 2003 Neural Networks and Signal Processing, 2003. Proceedings of the 2003 International Conference on 1 663 666 Vol.1 ofdm pilot system