Sat, 26 Jul 2008 06:14:14 BST CiteULike: dcastro's Kuo http://www.citeulike.org/user/dcastro/author/Kuo CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/3037909 <i>Communications, 2003. ICC '03. IEEE International Conference on, Vol. 4 (2003), pp. 2411-2415 vol.4.</i><br /><br />The problem of joint blind channel estimation and multiple access interference (MAI) suppression for an asynchronous code-division multiple-access (CDMA) system is studied. A low-complexity sliding-window scheme based on the expectation maximization (EM) algorithm is developed for joint blind maximum a posteriori probability (MAP) multi-user detection (MUD) and stochastic maximum likelihood (ML) channel estimation in a dispersive fading channel. With multi-stage soft interference cancellation, MAI can be efficiently suppressed. Together with an initial value prediction method for algorithm initialization at each window, the proposed scheme can track fading channels on the fly with no phase ambiguities even when channel gains are close to zero. Joint channel estimation and multiuser detection for multipath fading channels in DS-CDMA Sau-Hsuan Wu U Mitra CCJ Kuo Communications, 2003. ICC '03. IEEE International Conference on, Vol. 4 (2003), pp. 2411-2415 vol.4. 2008-07-23T22:50:34-00:00 2003 Communications, 2003. ICC '03. IEEE International Conference on 4 2411 2415 vol.4 cdma channel estimation http://www.citeulike.org/user/dcastro/article/2839865 <i>Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 3A (2005), pp. 798-801 vol. 3A.</i><br /><br />An FDTD method, combined with thin wire and thin slot algorithms used to analyze a metamaterial based on periodic mushroom structures, is proposed. This proposed method is suitable for analyzing problems with fine structural details. Two examples of mushroom structures are investigated to compare the results between simulation and measurement to show left-handed propagation properties. Accuracy of the proposed method is verified compared to the measurement results. Efficient FDTD method for analysis of left-handed mushroom structure Wei-Yang Wu A Lai KMKH Leong Chih-Wen Kuo T Itoh doi:10.1109/APS.2005.1552377 Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 3A (2005), pp. 798-801 vol. 3A. 2008-05-28T06:58:07-00:00 2005 Antennas and Propagation Society International Symposium, 2005 IEEE 3A 798 801 vol. 3A crlh fdtd metamaterial mushroom http://www.citeulike.org/user/dcastro/article/2782032 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1331-1337.</i><br /><br />This paper presents a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations. Based on resonance characteristics of a stepped impedance resonator (SIR), the second resonant frequency can be tuned over a wide range by adjusting its structure parameters. Emphasis is placed on filter synthesis for simultaneously matching in-band response and singly loaded Q by using tapped input/output couplings for the two designated passbands. Fractional bandwidth design graphs are used to determine proper geometric parameters of each coupled stage when filter specification is given. Realizable fractional bandwidths of the two passbands for a coupled SIR structure are clearly depicted in fractional bandwidth design graphs. Several experimental filters are fabricated and measured to demonstrate the design. Design of microstrip bandpass filters with a dual-passband response Jen-Tsai Kuo Tsung-Hsun Yeh Chun-Cheng Yeh doi:10.1109/TMTT.2005.845765 Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1331-1337. 2008-05-09T23:51:22-00:00 2005 Microwave Theory and Techniques, IEEE Transactions on 53 4 1331 1337 bandpass filter microstrip http://www.citeulike.org/user/dcastro/article/2625540 <i>Proceedings of the IEEE, Vol. 95, No. 7. (2007), pp. 1394-1427.</i><br /><br />Orthogonal frequency division multiple access (OFDMA) has recently attracted vast research attention from both academia and industry and has become part of new emerging standards for broadband wireless access. Even though the OFDMA concept is simple in its basic principle, the design of a practical OFDMA system is far from being a trivial task. Synchronization represents one of the most challenging issues and plays a major role in the physical layer design. The goal of this paper is to provide a comprehensive survey of the latest results in the field of synchronization for OFDMA systems, with tutorial objectives foremost. After quantifying the effects of synchronization errors on the system performance, we review some common methods to achieve timing and frequency alignment in a downlink transmission. We then consider the uplink case, where synchronization is made particularly difficult by the fact that each user's signal is characterized by different timing and frequency errors, and the base station has thus to estimate a relatively large number of unknown parameters. A second difficulty is related to how the estimated parameters must be employed to correct the uplink timing and frequency errors. The paper concludes with a comparison of the reviewed synchronization schemes in an OFDMA scenario inspired by the IEEE 802.16 standard for wireless metropolitan area networks. Synchronization Techniques for Orthogonal Frequency Division Multiple Access (OFDMA): A Tutorial Review M Morelli CCJ Kuo MO Pun doi:10.1109/JPROC.2007.897979 Proceedings of the IEEE, Vol. 95, No. 7. (2007), pp. 1394-1427. 2008-04-03T09:10:22-00:00 2007 Proceedings of the IEEE 95 7 1394 1427 ofdma synchronization tutorial http://www.citeulike.org/user/dcastro/article/2700985 <i>Global Telecommunications Conference, 2005. GLOBECOM '05. IEEE, Vol. 5 (2005), 5 pp..</i><br /><br />In this work we consider the uplink of an OFDMA system and present a novel receiver that performs joint frequency offset acquisition, channel estimation and data detection for each active user. The proposed receiver can be used with any subcarrier assignment scheme, and it operates in an iterative fashion. Users' separation is accomplished at the base station through space-alternating generalized-expectation (SAGE) techniques. Each separated user's signal is then passed to an expectation-conditional maximization (ECM)-based processor that jointly performs frequency acquisition, channel estimation and data detection at each iteration. Compared to conventional OFDMA systems, the proposed receiver allows significant reduction of the synchronization overhead as it dispenses from the need of returning estimated frequency offsets back to active users for frequency adjustment. Simulations indicate that the proposed scheme provides accurate data detection for unsynchronized OFDMA uplink transmissions over doubly-selective fading channels. A novel iterative receiver for uplink OFDMA Man-On Pun M Morelli CCJ Kuo doi:10.1109/GLOCOM.2005.1578244 Global Telecommunications Conference, 2005. GLOBECOM '05. IEEE, Vol. 5 (2005), 5 pp.. 2008-04-22T11:27:43-00:00 2005 Global Telecommunications Conference, 2005. GLOBECOM '05. IEEE 5 5 pp. ofdma receiver uplink http://www.citeulike.org/user/dcastro/article/2424806 <i>Communications, IEEE Transactions on, Vol. 54, No. 4. (2006), pp. 726-736.</i><br /><br />Maximum-likelihood estimation of the carrier frequency offset (CFO), timing error, and channel response of each active user in the uplink of an orthogonal frequency-division multiple-access system is investigated in this study, assuming that a training sequence is available. The exact solution to this problem turns out to be too complex for practical purposes as it involves a search over a multidimensional domain. However, making use of the alternating projection method, we replace the above search with a sequence of mono-dimensional searches. This results in an estimation algorithm of a reasonable complexity which is suitable for practical applications. As compared with other existing semi-blind methods, the proposed algorithm requires increased overhead but has more flexibility as it can be used with any subcarrier assignment scheme. Simulations indicate that the accuracy of the CFO estimates asymptotically achieves the Cramer-Rao bound. Maximum-likelihood synchronization and channel estimation for OFDMA uplink transmissions MO Pun M Morelli CCJ Kuo doi:10.1109/TCOMM.2006.873093 Communications, IEEE Transactions on, Vol. 54, No. 4. (2006), pp. 726-736. 2008-02-25T09:32:29-00:00 2006 Communications, IEEE Transactions on 54 4 726 736 channel estimation ml ofdma synchronization uplink