Thu, 24 Jul 2008 23:24:01 BST CiteULike: dcastros Hsieh http://www.citeulike.org/user/dcastro/author/Hsieh CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/2877965 <i>Consumer Electronics, IEEE Transactions on, Vol. 44, No. 1. (1998), pp. 217-225.</i><br /><br />The channel estimation methods for OFDM systems based on a comb-type pilot sub-carrier arrangement are investigated. The channel estimation algorithm based on comb-type pilots is divided into pilot signal estimation and channel interpolation. The pilot signal estimation based on LS or MMSE criteria, together with channel interpolation based on piecewise-linear interpolation or piecewise second-order polynomial interpolation is studied. Owing to the MMSE estimate of the pilot signals, the inter-carrier interference and additive white Gaussian noise are reduced considerably. The computational complexity of pilot signal estimation based on MMSE criterion can be reduced by using a simplified LMMSE estimator with low-rank approximation using singular value decomposition. Phase compensators before and after interpolation are also presented to combat the phase changes of subchannel symbols arising from the frame synchronization errors. Compared to the transform-domain processing based channel estimation algorithm the MMSE estimate of pilot signals together with phase compensated linear interpolation algorithm provides a better performance and requires less computations Channel estimation for OFDM systems based on comb-type pilot arrangement in frequency selective fading channels Meng-Han Hsieh Che-Ho Wei doi:10.1109/30.663750 Consumer Electronics, IEEE Transactions on, Vol. 44, No. 1. (1998), pp. 217-225. 2008-06-09T19:36:24-00:00 1998 Consumer Electronics, IEEE Transactions on 44 1 217 225 channel estimation ofdm pilot http://www.citeulike.org/user/dcastro/article/2877954 <i>Industrial Electronics, IEEE Transactions on, Vol. 43, No. 6. (1996), pp. 609-615.</i><br /><br />Phase-locked loop (PLL) is a technique which has contributed significantly toward the technology advancement in communication and motor servo control systems in the past 30 years. Inventions in PLL schemes combined with novel integrated circuit (IC) technology have made PLL devices important system components. The development of better modular PLL ICs is continuing. As a result, it is expected that they will contribute to the improvement in performance and reliability of future communication systems. They will also contribute to the development of higher accuracy and higher reliability servo control systems, such as those involved in machine tools. This paper provides a concise review of the basic PLL principles applicable to communication and servo control systems, gives the configurations of PLL applications and reports a number of popular PLL chips Phase-locked loop techniques. A survey Guan-Chyun Hsieh JC Hung doi:10.1109/41.544547 Industrial Electronics, IEEE Transactions on, Vol. 43, No. 6. (1996), pp. 609-615. 2008-06-09T19:33:05-00:00 1996 Industrial Electronics, IEEE Transactions on 43 6 609 615 overview pll http://www.citeulike.org/user/dcastro/article/2819803 <i>Communications, IEEE Transactions on, Vol. 44, No. 6. (1996), pp. 668-674.</i><br /><br />This paper considers discrete time analyses of digital delay lock loops (DDLL), and presents the results of an investigation concerning the performance degradation due to Doppler. The performance measures evaluated include the steady-state timing error probability density function (PDF) and the mean time to lose lock. The linear approximations are also provided and compared to the numerical results and simulations. The delay lock loop is a well-known technique to track the pseudo-noise (PN) codes for spread spectrum systems. Under a severe Doppler environment, such as in the low Earth orbit (LEO) satellite communication, it will be difficult to track the PN code for the first-order loop. Since the digital systems are more compact, lower cost, and more stable than their analog counterparts, we focus our attention on the digital first and second order code tracking loops that suffer from severe Doppler Performance analysis of digital delay lock loops in the presence of Doppler shift Nan-Yang Yen Szu-Lin Su Sheng-Cheng Hsieh doi:10.1109/26.506383 Communications, IEEE Transactions on, Vol. 44, No. 6. (1996), pp. 668-674. 2008-05-21T12:54:49-00:00 1996 Communications, IEEE Transactions on 44 6 668 674 dll doppler tracking http://www.citeulike.org/user/dcastro/article/2819802 <i>Communications, 1995. ICC '95 Seattle, 'Gateway to Globalization', 1995 IEEE International Conference on, Vol. 3 (1995), pp. 1896-1900 vol.3.</i><br /><br />The delay lock loop is a well-developed technique to track the pseudo-noise codes for spread-spectrum systems. In previous papers the first-order loop was analyzed in the absence of Doppler shift. However, under severe Doppler environment, such as low-earth-orbit (LEO) satellite communication, the tracking of PN code will be difficult for the first-order loop. This paper considers discrete time analyses of first- and second-order digital delay lock loops (DDLL), and presents the results of an investigation concerning the performance degradation due to Doppler. The performance measures evaluated include the steady-state timing error probability density function (pdf) and the mean time to lose lock. The measures are characterized in terms of the Doppler shift and the loop signal-to-noise ratio. Moreover, approximate expressions for the steady-state timing error probability density and the mean time to lose lock are also presented for the first- and second-order digital delay lock loops. The analyses are confirmed by numerical results and simulation Performance analysis of digital delay lock loops in the presence of Doppler shift Szu-Lin Su Nan-Yang Yen Sheng-Cheng Hsieh doi:10.1109/ICC.1995.524527 Communications, 1995. ICC '95 Seattle, 'Gateway to Globalization', 1995 IEEE International Conference on, Vol. 3 (1995), pp. 1896-1900 vol.3. 2008-05-21T12:54:47-00:00 1995 Communications, 1995. ICC '95 Seattle, 'Gateway to Globalization', 1995 IEEE International Conference on 3 1896 1900 vol.3 dll doppler tracking http://www.citeulike.org/user/dcastro/article/2782029 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 51, No. 4. (2003), pp. 1241-1246.</i><br /><br />This paper presents a new compact, low insertion-loss, sharp-rejection, and wide-band microstrip bandpass filter. A bandstop filter is introduced that uses a ring resonator with direct-connected orthogonal feed lines. A new bandpass filter based on the bandstop filter uses two tuning stubs to construct a wide-band passband with two sharp stopbands. Without coupling gaps between feed lines and rings, there are no mismatch and radiation losses between them and, therefore, the new filters show low insertion loss. In addition, a dual-mode characteristic is used to increase the stopband bandwidth of the new filters. A simple transmission-line model used to calculate the frequency responses of the filters shows good agreement with measurements. The filter using three cascaded rings has 3-dB fractional bandwidth of 49.3%, an insertion loss of better than 1.6 dB in the passband, a return loss of larger than 13 dB from 4.58 to 7.3 GHz, and two rejections of greater than 40 dB within 2.75-4.02 and 7.73-9.08 GHz. The high-performance, compact-size, and low-cost filter was designed for reducing the interference in full duplex systems in satellite communications. Compact, low insertion-loss, sharp-rejection, and wide-band microstrip bandpass filters Lung-Hwa Hsieh Kai Chang doi:10.1109/TMTT.2003.809643 Microwave Theory and Techniques, IEEE Transactions on, Vol. 51, No. 4. (2003), pp. 1241-1246. 2008-05-09T23:50:43-00:00 2003 Microwave Theory and Techniques, IEEE Transactions on 51 4 1241 1246 bandpass compact filter loss low microstrip http://www.citeulike.org/user/dcastro/article/2774494 <i>Electronics Letters, Vol. 34, No. 12. (1998), pp. 1170-1171.</i><br /><br />A novel technique for obtaining dual-band circular polarisation (CP) radiation of a single-feed circular microstrip antenna is proposed and demonstrated. By embedding two pairs of arc-shaped slots of proper lengths close to the boundary of a circular patch, and protruding one of the arc-shaped slots with a narrow slot, the circular microstrip antenna can perform dual-band CP radiation using a single probe feed. Details of the antenna design and experimental results are presented Single-feed dual-band circularly polarised microstrip antenna Gui-Bin Hsieh Ming-Huang Chen Kin-Lu Wong Electronics Letters, Vol. 34, No. 12. (1998), pp. 1170-1171. 2008-05-09T06:38:11-00:00 1998 Electronics Letters 34 12 1170 1171 antenna circularly dual-band microstrip polarisation http://www.citeulike.org/user/dcastro/article/2762253 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 2. (2002), pp. 453-460.</i><br /><br />A transmission-line model is used to extract the equivalent lumped-element circuits for the closed- and open-loop ring resonators. The unloaded Q values of the ring resonators can be calculated from the equivalent lumped elements G, L, and C. Four different configurations of microstrip ring resonators fabricated on low and high dielectric-constant substrates are used to investigate the lumped elements and unloaded Qs. The largest difference between the measured and calculated unloaded Q is 5.7%, which is due to measurement uncertainties and accuracies of the calculation. These simple expressions introduce an easy method for analyzing ring resonators in filters and provide, for the first time, a means of predicting their unloaded Q Equivalent lumped elements G, L, C, and unloaded Q's of closed- and open-loop ring resonators Lung-Hwa Hsieh Kai Chang doi:10.1109/22.982223 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 2. (2002), pp. 453-460. 2008-05-06T18:35:53-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 2 453 460 lumped resonator ring http://www.citeulike.org/user/dcastro/article/2709648 <i>Computer Communications and Networks, 2007. ICCCN 2007. Proceedings of 16th International Conference on (2007), pp. 888-893.</i><br /><br />In this paper an efficient channel estimation algorithm under different mobile velocities in orthogonal frequency division multiplexing (OFDM) systems is considered. Conventional channel estimation algorithms track adaptively time-varying channels using high performance approaches. However, the power consumption for these algorithms are usually tremendous. On the other hand, users usually move with low speeds in most cases and they do not require such a complicated channel tracker. In view of this we classify the moving speeds into three modes. We then propose a multi-mode channel tracking scheme with different complexities and tracking capabilities. A novel inverse mean-square error (IMSE) velocity metric estimator is also provided along with a mode selection procedure to detect the proper tracking mode. Simulation results show that under the OFDMA mode of the IEEE 802.16e-2005 standard, the proposed algorithm can track the velocity variation very well and perform channel estimation using the most efficient tracking mode. The power consumption is thus decreased significantly without degrading the system performance. An Efficient Multi-Mode Channel Tracking Scheme under Different Velocities in OFDM Systems Yu-Tao Hsieh Pang-An Ting doi:10.1109/ICCCN.2007.4317930 Computer Communications and Networks, 2007. ICCCN 2007. Proceedings of 16th International Conference on (2007), pp. 888-893. 2008-04-23T17:53:28-00:00 2007 Computer Communications and Networks, 2007. ICCCN 2007. Proceedings of 16th International Conference on 888 893 channel estimation mobile ofdm http://www.citeulike.org/user/dcastro/article/2425849 <i>Vehicular Technology, IEEE Transactions on, Vol. 48, No. 5. (1999), pp. 1596-1609.</i><br /><br />This paper presents a fast low-complexity synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems over fading channels. By utilizing the guard interval in OFDM signals, the frame synchronization and the frequency offset estimation are considered simultaneously. The implementation can be simplified by only using the sign bits of the in-phase and the quadrature components of the received OFDM signal for frame synchronization and frequency offset compensation. A frequency-offset independent frame synchronization algorithm is derived, and a low-complexity frequency offset estimator based on the synchronized correlator output is presented in this paper. Due to the subcarrier ambiguity in the guard-interval-based (GIB) frequency detector, the maximum correctable frequency range is limited to ±1/2 of the subcarrier spacing. In this paper, we also present a new frequency acquisition scheme that can solve the subcarrier ambiguity problem and extend the frequency acquisition range to nearly a half of the useful OFDM signal bandwidth A low-complexity frame synchronization and frequency offset compensation scheme for OFDM systems over fading channels Meng-Han Hsieh Che-Ho Wei doi:10.1109/25.790537 Vehicular Technology, IEEE Transactions on, Vol. 48, No. 5. (1999), pp. 1596-1609. 2008-02-25T15:34:35-00:00 1999 Vehicular Technology, IEEE Transactions on 48 5 1596 1609 channel fading frame frequency low multipath ofdm offset synchronization