Patent ID: 8422538

Claim:
A channel estimation method for an OFDM (Orthogonal Frequency Division Multiplexing) relaying system, which is based on an EM (Expectation Maximization) algorithm and applied to an AF (Amplify-and-Forward) OFDM relaying system, wherein channels from a source node to a relaying system and from the relaying system to a destination node in a wireless communication system are respectively estimated at the destination, wherein the channel estimation method comprises steps of: constructing a system model, wherein the channels from the source node to the relaying system and from the relaying system to the destination node are respectively constructed, and wherein a matrix-form unit converts signals into a matrix form for channel estimation, and the signal received by the destination node is expressed by y n d = ⁢ ∑ l = 0 L d - 1 ⁢ h l d ⁢ x n - l r + w n d = ⁢ 1 N ⁢ ∑ k = 0 N - 1 ⁢ ( ⁢ ∑ l = 0 L d - 1 ⁢ h l d ⁢ ⅇ - j2π ⁢ ⁢ kl / N ) ⁢ ( ⁢ ∑ l = 0 L r - 1 ⁢ h l r ⁢ ⅇ - j2π ⁢ ⁢ kl ′ / N ) ⁢ α k ⁢ d k ⁢ ⅇ j2π ⁢ ⁢ kn / N + ⁢ 1 N ⁢ ∑ k = 0 N - 1 ⁢ ( ⁢ ∑ l = 0 L d - 1 ⁢ h l d ⁢ ⅇ - j2π ⁢ ⁢ kl / N ) ⁢ α k ⁢ W k r ⁢ ⅇ j2π ⁢ ⁢ kn / N + w n d , ⁢ 0 ≤ n ≤ N - 1 ; setting an expectation function, wherein an expectation setting unit sets the expectation function; performing maximization processing, wherein a maximization processing unit performs the maximization processing on the expectation function; and performing iteration, wherein a result of the maximization processing unit is returned to the expectation setting unit for an iteration to modify the expectation function until a predetermined number of iterations is completed.