Sunplus Mmobile Inc.

Industrial Technology Research Institute

Chung Shan Institute of Science and Technology

Shin-Yuan Wang

Shin-Lin Shieh

Po-Ying Chen

Wei-De Wu

Chia-Chi Huang

Hui-Ming Wang

Yuh-Maiw Jong

Weily Kuo

Kai-Jie Yang

Xiu-Sheng Li

A Doppler frequency estimation system includes a basis projector, a polynomial generator and an extreme value determinator. The basis projector receives and projects multiple channel sampling signals to a set of orthogonal bases to thereby generate multiple channel correlation vectors. The polynomial generator is connected to the basis projector in order to produce a target polynomial based on the channel correlation vectors, an estimated channel-envelope-to-noise-plus-interference power-ratio and a channel-envelope power. The extreme value determinator is connected to the polynomial generator in order to determine an extreme value of the polynomial and output a frequency corresponding to the extreme value as an estimated Doppler frequency.

Doppler frequency estimation system and method

A method for calculating coefficients of a filter and a method for filtering are provided. The invention directly factorizes a specific function in a cepstrum domain by spectral factorization and cepstrum technique to obtain coefficients of denominator function from the filter. In other words, the invention adopts a non-iterative algorithm to reduce computational complexity and avoid convergence due to calculating coefficients. Besides, the specific function of the invention includes a compensation function, so that a Fourier transform with greatly reduced size can be utilized in the spectral factorization to greatly save the computations and keep good system performance at a receiver.

Code division multiple access (CDMA) system for calculating coefficients of filter and method for filtering a received signal

This invention relates to an equalization apparatus and an equalization method. A plurality of equalizers is applied to the equalization apparatus to eliminate interferences of multiple clusters in a channel. The weights of the equalizers are calculated under minimum mean square error criterion by gains of delay paths of multiple clusters in the whole channel. Therefore, the interference of different clusters in the whole channel can be greatly eliminated.

Method and apparatus for equalization in clustered channels

A method for mitigating interference is provided. First, a received signal having a training sequence is received from a transmitter. Then, a Signal-to-Interference-plus-Noise Ratio (SINR) of the training sequence in the received signal is calculated, and whether a co-channel interference signal exists in the received signal is determined according to the SINR. The signal power corresponding to each time index in the received signal is calculated to detect a beginning time point and an ending time point of the co-channel interference signal. Finally, when the co-channel interference signal in the received signal is detected, the time when an interference cancellation filter is turned on is determined by the beginning time point and the ending time point.

Method for mitigating interference

This invention relates to an equalization apparatus, an equalization method and a receiver using the same. Two equalizers are applied to the equalization apparatus to cover two clusters of a channel. The weights of the two equalizers are calculated by channel gains of the whole channel based on the minimum mean square error criterion. Therefore the interference of the whole channel due to different clusters can be reduced enormously.

Equalization apparatus, equalization method and receiver using the same

A method and apparatus having a modified Reed-Solomon decoder is used for finding a specific code group used by a base station and the frame timing synchronization with the base station. The modified Reed-Solomon decoder uses a standard Reed-Solomon decoder and some reliability measurements computed from the received code word symbols. If the reliability of a received symbol is too low, this symbol is considered as erasure. By selecting code word symbols with higher reliabilities and erasing code word symbols with lower reliabilities, the symbol error probability is reduced and the performance is improved. Several modified Reed-Solomon decoders and a few decoding strategies are introduced in order to decode the received code word sequences with a power- and memory-effective method.

Method and apparatus for code group identification and frame synchronization by use of Reed-Solomon decoder and reliability measurement for UMTS W-CDMA

A method and an architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system are disclosed. In the present invention, the carrier frequency offset is divided into an integer part and a fractional part, wherein the integer part is defined as integer multiples of the reciprocal of the period of a spreading code. The integer part of the carrier frequency offset can be obtained by matching received signals with a spreading code whose central frequency is located at integer multiples of the reciprocal of the period of the spreading code and searching the one, of the matched results, with the largest amplitude. Besides, a direction flag can be obtained by comparing the amplitude of the searched one with that of the matched results neighboring the searched one. After correcting the integer part carrier frequency offset, the difference between the phase angles of two successive matched results can be calculated and used to calculate the fractional part of the carrier frequency offset according to the direction sag. After the carrier frequency offset is corrected, the correction of the timing offset of the spreading code can be made by searching for the first path of the channel impulse response which produces the minimum delay spread.

Method and architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system

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Hsinchu, Taiwan

Shin-Yuan Wang