Lucent Technologies Inc.

At&t Bell Laboratories

Bell Telephone Laboratories

Alcatel-lucent USA Inc.

At&t Company

At&t Information Systems Inc. Bell Telephone Laboratories, Inc.

Jack Salz

Thomas L Marzetta

Michael Edward Prise

Sanjay Kasturia

Cecil William Farrow

Gerard Joseph Foschini

Aiyou Chen

Laurence Eugene Mailaender

Isam M Habbab

Sivarama Krishnan Venkatesan

Mohsen Kavehrad

Vittorio Comino

Jean J Werner

Ravi Subramanian

A method for transmitting a sequence of data blocks of equal length includes obtaining part of a matrix for the impulse response function of a communication channel between a transmitter and a receiver. The part relating to channel-induced interference between sampling intervals of adjacent ones of the data blocks. The method includes designing a set of one or more linearly independent waveforms based on the obtained part of the matrix for the impulse response function and transmitting a sequence of the data blocks over the channel from the transmitter to the receiver. Each data block of the sequence is a weighted linear superposition of the one or more waveforms of the designed set.

Channel-adaptive waveform modulation

Generally, a method and apparatus are provided for computing a matrix inverse square root of a given positive-definite Hermitian matrix, K. The disclosed technique for computing an inverse square root of a matrix may be implemented, for example, by the noise whitener of a MIMO receiver. Conventional noise whitening algorithms whiten a non-white vector, X, by applying a matrix, Q, to X, such that the resulting vector, Y, equal to Q&#xb7;X, is a white vector. Thus, the noise whitening algorithms attempt to identify a matrix, Q, that when multiplied by the non-white vector, will convert the vector to a white vector. The disclosed iterative algorithm determines the matrix, Q, given the covariance matrix, K. The disclosed matrix inverse square root determination process initially establishes an initial matrix, Q, by multiplying an identity matrix by a scalar value and then continues to iterate and compute another value of the matrix, Q, until a convergence threshold is satisfied. The disclosed iterative algorithm only requires multiplication and addition operations and allows incremental updates when the covariance matrix, K, changes.

Method and apparatus for determining an inverse square root of a given positive-definite hermitian matrix

DC offset cancellation and timing recovery is provided in a homodyne receiver. The homodyne receiver demodulates an RF signal to produce a baseband signal. An initial offset correction module determines an initial DC offset of the baseband signal. An initial offset correction is applied to the baseband signal to provide an initial corrected baseband signal. Wherein, a dynamic DC offset correction module determines a dynamic DC offset. A dynamic DC offset correction is applied to the initial corrected baseband signal providing a dynamic corrected baseband signal. A timing signal is acquired from the baseband signal for synchronizing the receiver to a transmitter. A method for correcting DC offset of a baseband signal in a homodyne receiver is also described.

Offset correction for a homodyne radio

Data-aided equalization and cancellation in digital data transmission over dually polarized fading radio channels is disclosed. The present invention uses decision feedback structures with finite-tap transversal filters. Subject to the assumption that some past and/or future data symbols are correctly detected, formulas and algorithms for evaluating the least mean-square error for different structures are disclosed. In a sequence of curves, the performance of various structures for a particular propagation model and several fading events are evaluated and compared.

Combined cross polarization interference cancellation and intersymbol

A method and apparatus for rapid initialization of the transversal filter efficients in an echo canceler or echo measurement device is described. During initialization, a first data sequence is applied to a transmission channel, and an error signal representing the difference between the resulting echo and a replica thereof generated by the transversal filter is formed. The coefficients used to form the replica (in the case of an echo canceler) or to model the transmission channel (in the case of an echo measurement device) are then updated as a function of the error and a second data sequence which is orthogonal to the first sequence.

Fast start-up of adaptive echo canceler or echo measurement device

Combined amplitude and frequency-shift-keying (AM-FSK) modulation of a carrier wave by a baseband data signal achieves significant suppression of one of the sidebands to ease the design requirements of filters generally used in the transmission of FSK signals. The significant suppression effect is observed when the ratio of minimum to maximum amplitude of the envelope of the amplitude modulated carrier wave is restrained to be approximately between 0.6 and 0.9. In one embodiment amplitude modulation is performed by a pair of amplifiers, each having a predetermined gain. In another embodiment, an all digital technique is used to synthesize the AM-FSK signal.

Amplitude and frequency modulation system

Growing community of inventors

Fair Haven, NJ, United States of America

Jack Salz