Patent ID: 7333549
Filing Date: 2008-02-19
Classification: H04L

Abstract:
1. A method for estimating a sequence of transmitted quadrature amplitude modulation (QAM)-modulated signals and space-time block coded signals using an optimal expectation-maximization (EM)-based iterative estimation algorithm in a multiple-input and multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) mobile communication system, comprising the steps of: (a) producing an initial sequence estimation value according to a predetermined initial value using a pilot sub-carrier contained in each OFDM signal received by a receiving side; (b) producing a nonnalized value of the received signal on a channel-by-channel basis using orthogonality between the OFDM signals received by the receiving side, the normalized value of the received signal being produced by a predetermined equation; (c) producing at least one subsequent sequence estimation value using the initial sequence estimation value and the normalized value of the received signal on the channel-by-channel basis; and (d) if the at least one subsequent sequence estimation value converges to a constant value, designating the converged subsequent sequence estimation value to be a final sequence estimation value, wherein the predetermined equation is given by: where “w n,m ” denotes a white Gaussian noise of a channel from an n th transmitting antenna to an m th receiving antenna, “F” denotes a discrete Fourier transform matrix, and “h n,m ” denotes an impulse response associated with the channel from the nth transmitting antenna to the m th receiving antenna.