Other

At&t Intellectual Property I, LP

At+t Corp.

Christine Fragouli

William Turin

Naofal Mohammed Al-Dhahir

The burden of designing multiple training sequences for systems having multiple transmit antennas, is drastically reduced by employing a single sequence from which the necessary multiple sequences are developed. The single sequence is selected to create sequences that have an impulse-like autocorrelation function and zero cross correlations. A sequence of any desired length Ncan be realized for an arbitrary number of channel taps, L. The created sequences can be restricted to a standard constellation (that is used in transmitting information symbols) so that a common constellation mapper is used for both the information signals and the training sequence. In some applications a training sequence may be selected so that it is encoded with the same encoder that is used for encoding information symbols. Both block and trellis coding is possible in embodiments that employ this approach.

Training-based channel estimation for multiple-antennas

The burden of designing multiple training sequences for systems having multiple transmit antennas, is drastically reduced by employing a single sequence from which the necessary multiple sequences are developed. The single sequence is selected to create sequences that have an impulse-like autocorrelation function and zero cross correlations. A sequence of any desired length Ncan be realized for an arbitrary number of channel taps, L. The created sequences can be restricted to a standard constellation (that is used in transmitting information symbols) so that a common constellation mapper is used for both the information signals and the training sequence. In some applications a a training sequence may be selected so that it is encoded with the same encoder that is used for encoding information symbols. Both block and trellis coding is possible in embodiments that employ this approach.

A training sequence is created for space-time diversity arrangement, having any training sequence length, while limiting the training sequence to a standard constellation. Given a number of channel unknowns that need to be estimated, L, a training sequence can be creates that yields minimum means squared estimation error for lengths N=kN+L&#x2212;1, for any positive integer k&#x2267;1, where Nis a selected perfect roots-of-unity sequence (PRUS) of length N. The training sequence is created by concatenating k of the length N perfect roots-of-unity sequences, followed by L&#x2212;1 initial symbols of that same PRUS. Good training sequences can be created for lengths Nthat cannot be obtained through the above method by concatenating a requisite number of symbols found through an exhaustive search.

Creating training sequences for space-time diversity arrangements

A training sequence is created for space-time diversity arrangement, having any training sequence length, while limiting the training sequence to a standard constellation. Given a number of channel unknowns that need to be estimated, L, a training sequence can be creates that yields minimum means squared estimation error for lengths N=kN+L&#x2212;1, for any positive integer k&#x2266;1, where Na selected perfect roots-of-unity sequence (PRUS) of length N. The training sequence is created by concatenating k of the length N perfect roots-of-unity sequences, followed by L&#x2212;1 initial symbols of that same PRUS. Good training sequences can be created for lengths Nthat cannot be obtained through the above method by concatenating a requisite number of symbols found through an exhaustive search.

Growing community of inventors

Madison, NJ, United States of America

Christine Fragouli