Browsing by Author "Hung Kun-Chien"

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Channel estimation technique for multi-carrier system
(2012-03-20)
Hung Kun-Chien
;
Lin David W.
The present invention relates to a channel estimation technique for multi-carrier system which uses pilot signal to first obtain pilot subcarrier channel responses, then estimate the mean delay and the root-mean-square delay spread of the channel, and then uses interpolation to obtain the channel responses of arbitrary subcarriers. The present invention is able to perform channel estimation and to accurately estimate various channel delay parameters (such as the initial delay, the mean delay, and the root-mean-square delay spread) with very low quantity of pilot signal and with low computational complexity. In addition, the present invention has broad applicability, as it does not require the channel power-delay profile to be of certain specific types and it can operate in systems where pilot subcarriers have an irregular configuration.
Method for OFDM and OFDMA channel estimation
(2012-07-10)
Hung Kun-Chien
;
Lin David W.
This invention discloses a method for OFDM and OFDMA channel estimation via phase-rotated polynomial interpolation and extrapolation (inter/extra-polation). For complexity reason, polynomial inter/extra-polation is an often considered method for channel estimation in orthogonal frequency-division multiplexing (OFDM) and orthogonal frequency-division multiple access (OFDMA) systems, in which the simplest choice is linear inter/extra-polation. But the performance of this method depends on the accuracy of symbol timing estimation as well as the channel delay spread. The invention mitigates the problem by adding a linear phase factor to polynomial inter/extra-polation, which corresponds to adding a delay (also called delay shift) in the time domain.
Preamble sequence detection and integral carrier frequency offset estimation method for OFDM/OFDMA wireless communication system
(2012-10-30)
Hung Kun-Chien
;
Lin David W.
A preamble sequence detection and integral carrier frequency offset estimation method for OFDM/OFDMA wireless communication systems by formulating integral carrier frequency offset estimation and preamble sequence detection as a signal detection problem in multi-channel interference, obtaining the theoretically optimal solution, and deriving simplified, approximately optimal solutions, in which frequency-domain filtering is employed to calculate the required correlation values, which can drastically reduce the high computational complexity of the original theoretically optimal solution but result in little impact on precision. In addition, several further simplified algorithms are provided, some of which can even eliminate the use of multipliers. The using of frequency-domain filtering has high extensibility in application to related signal sequence detection problems.