Lucent Technologies Inc.

At+t Corp.

Bae Systems Information and Electronic Systems Integration Inc.

Alcatel Lucent

Charles Robert Giardina

Ashok N Rudrapatna

Gary R Lomp

Jaehyeong Kim

Barnet M Schmidt

Haobo Lai

Training sequences, for transmittal with an individual data packet via a wireless communication channel, enable estimation of the channel impulse response (CIR) to provide values usable for correction of multipath and other transmission disturbances with enhanced security and avoidance of complex processing. Training sequences employing several groupings of pseudonoise sequences enable a receiver to derive several observations of the CIR for each data packet received. Averaging of values of the several CIR estimations provides a CIR estimation of increased accuracy usable in determining coefficients to adjust taps of an adaptive equalizer for signal correction for the data of the packet. Training sequences with use of distinct pseudonoise sequences in several individual groupings enhance security, while simplifying processing by avoidance of necessity for multiplication or division of complex functions. Training sequences, systems and methods are described.

Training sequences, methods and wireless communication systems providing security-enhanced initialization

Channel impulse response estimation employs a training sequence to enable correction for multipath and other disturbances affecting a signal during transmission via a digital wireless communication channel. High-speed packet transmission rates, with a training sequence for each packet, are made possible by training sequence construction enabling fast algorithm processing of received signals for impulse response estimation. Upon reception, a Toeplitz-type mathematical representation is constructed based on transmitted and received versions of a training sequence. The Toeplitz-type representation may then be processed by application of fast algorithms, such as Levinson-type algorithms, to determine coefficients representative of the communication channel impulse response. These coefficients, applied to an adaptive equalizer type of filter, enable correction for signal disturbances incurred in transmission. Channel impulse response estimation methods and systems are described.

Transmission channel impulse response estimation using fast algorithms

A predistortion system and method uses an inner predistortion function to adjust a signal being input into a distortion generating circuit and at least one outer predistortion function to adjust the signal being input into the inner predistortion function. Thus, the inner predistortion function can reduce the distortion from the distortion generating circuitry, and any remaining distortion can be reduced by the outer predistortion function.

Multiple stage and/or nested predistortion system and method

Quasi-Walsh function systems are developed which allow multiple access as well as spectral spreading for interception and jamming prevention. Mutual interference is minimal due to orthogonal spreading. High signal hiding capability occurs by utilizing a large number of distinct orthogonal codes. An encoding algorithm is presented which allows a simple way of &ldquo;keeping track&rdquo; of the different systems of Quasi-Walsh systems as well as determining appropriate values for given users at specified chip values.

Method of enhancing security for the transmission of information

In accord with the transmission system, encoded signals may be processed in intermediate stations and at receiving stations in an order different from the order of the original encoding process for transmission. In particular, the recovery of CDMA encoded signals does not require application of spreading/despreading codes in the original scheme or sequence of application of spreading codes. In one embodiment, code applications may be permuted without losing the original signal which has been encoded. In such applications, not all of the encoding spreading functions results in an increased spreading rate.

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Mahwah, NJ, United States of America

Charles Robert Giardina