Training-based channel estimation for multiple-antennas

摘要

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 Nt can 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.

主权项

1. A method comprising:
developing a plurality of symbol streams from an information stream; mapping symbols of said symbol streams onto a standard constellation to create a plurality of mapped streams; applying respective ones of the mapped streams to different ones of a plurality of antennas during a first time period; generating n training sequences from a training sequence, where n is an integer greater than one; mapping said n training sequences onto the standard constellation to create n mapped training sequences, where said n training sequences have a common length; and applying respective ones of the n mapped training sequences to different ones of said antennas during a second time period; wherein the training sequence is a root sequence composed of Nth roots of unity, where N is a power of 2 integer that is not smaller than L, where L is an integer and corresponds to a number of channel taps of a channel represented by a filter with L channel taps from each of said plurality of antennas to a receiver antenna.