Mediatek Corporation

Ho-chi Hwang

Wei-Nan Sun

Wei-nan Sun

Shang-Chieh Liu

Ching-Yao Su

A GSM communication system uses a channel estimator to generate a channel impulse response estimate from received bursts. Preferred embodiments of such a system include a first correlation unit that uses N midamble bits to evaluate received signals and produce first correlation outputs over a wide search range. A positioning unit identifies candidate first correlation outputs having the best estimation quality within a sliding observation window and uses those outputs as the initial channel impulse response (CIR) estimate. The initial CIR is provided to a second correlation unit that block correlates M (greater than N) midamble bits to the received signal samples. The second correlation unit performs correlation stage by stage with compensation based on the initial and updated CIR to improve the channel estimation.

Channel estimation in a wireless transmission system

A receiver includes a Viterbi-like equalizer that provides diversity combining of soft values to produce reliability information. The output reliability information at time k is the average of the first reliability information at time k and the second reliability information at time (k&#x2212;1) after being normalized by the noise power. The first reliability information at time k is the difference between the two accumulated metrics of the two preceding nodes arriving at the same node having the global minimum node metric at time k over all transitions of all states. The second reliability function at time k is the difference between the best accumulated metric characterized by the last (L&#x2212;1) bit being binary 'one' and the best accumulated metric characterized by the last (L&#x2212;1) bit being binary 'zero.'

Method and apparatus for generation of reliability information with diversity

Frequency synchronization bursts are detected for a radio communication system such as a GSM cellular telephone network using a two stage correlation process. A first unit performs a first set of correlations to identify receipt of the frequency synchronization burst. A preliminary identification is declared when the moving average of the first set of correlations, normalized for received power, exceeds a threshold value for a number of contiguous samples. After a preliminary identification is made, a second unit performs a second set of correlations to confirm the detection of the frequency synchronization burst. The second correlations are preferably also normalized and confirmation of detection is declared when the normalized moving average of the second stage correlation exceeds a threshold value for a number of contiguous samples.

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Hsin-Chu, Taiwan

Ho-chi Hwang