Lucent Technologies Inc.

Agere Systems Inc.

Yong J Lee

Mohsen Sarraf

Sheng-Jen Tsai

Nima Brardjanian

Robert Louis Cupo

Alex Matusevich

Mojtaba Shariat

Walid E Nabhane

A frame formatting technique for filling a fixed length master frame with a number of variable length frames and adding additional data to synchronize the individual variable length frames and increase the randomness of the fixed length master frame. The technique fills unused portions of the fixed length master frame with random data to maximize the randomness of the fixed length master frame which can be used to produce a well behaved modulated signal for digital broadcasting, thereby increasing the efficiency of digital broadcasting system.

Frame formatting technique

A simplified method for frequency offset estimation in a TDMA cellular PCS environment using &pgr;/4-shifted DQPSK comprises the steps of multiplying a complex conjugate of a received complex-valued symbol and a succeeding symbol to produce a comparison vector having an angle equal to the phase angle between the received complex-valued symbol and the succeeding symbol, rotating the comparison vector so that the angle thereof is between 0&deg; and 90&deg;, and estimating the frequency offset by determining a constant deviation of the phase angle from an ideal phase angle value of 45&deg; by calculating an average phase angle for a plurality of successive comparison vectors or correlating the rotated comparision vector against a bank of unit vectors to determine a maximum correlation.

Method and apparatus for frequency offset compensation

A simplified method for sampling timing adjustment and frequency offset estimation in a TDMA cellular PCS environment using &pgr;/4 - shifted DQPSK comprises the steps of oversampling a received signal resulting from transmission of sequences of complex-valued symbols at a rate N times the symbol rate thereof so as to produce N sets of samples, comparing for each set of samples the differential phase angle between successively received complex-valued symbols, and determining which set of the N sets of samples has differential phase angles closest to ideal values to thereby obtain an optimal sampling timing. The differential phase angles are measured by multiplying a complex conjugate of a received complex-valued symbol and a succeeding symbol to produce a comparison vector having an angle equal to the differential phase angle between the received complex-valued symbol and the succeeding symbol. The differential phase angles are optionally rotated so that the angle thereof is between 0&deg; and 90&deg;. Frequency offset is estimated by determining a constant deviation of the differential phase angles from an ideal differential phase angle value for a plurality of successive comparison vectors by correlating the rotated comparison vectors against a bank of unit vectors to determine a maximum correlation.

Method and apparatus for sampling timing adjustment and frequency offset compensation

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Holmdel, NJ, United States of America

Yong J Lee