Patent ID: 8331467
Filing Date: 2012-12-11
Classification: H04L

Abstract:
1. A method for estimating a radio channel in a OFDM-based radio communications system, comprising: receiving at a receiver a block of OFDM symbols transmitted from multiple antennas over multiple sub-carrier frequencies, where the block of OFDM symbols includes known pilot symbols and data symbols to be determined by the receiver and the pilot symbols are transmitted in a predetermined symmetric pattern at periodic times on periodic sub-carriers; processing the received block of OFDM symbols to determine a pilot channel estimate for each pilot symbol; forming an N×M matrix of points corresponding to the received OFDM symbol block, where N is the number of sub-carriers and M is the number of OFDM symbols in the OFDM symbol block, including inserting the pilot channel estimates at predetermined positions in the N×M matrix according to the predetermined symmetric pilot pattern and inserting a zero in remaining positions in the N×M matrix; calculating a two dimensional inverse Fourier transform of the N×M matrix resulting in multiple copies of a channel estimate in the time domain; selecting one of the copies of the channel estimate; and calculating a two dimensional Fourier transform of the selected channel estimate to obtain a channel estimate for each position in the N×M matrix without performing interpolation between the pilot symbols.