Patent Document ID: 20120069872
Application ID: 12886028
Patent Flag: 0

Claim One:
1. 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  - j2π kl / N ) ( ∑ l ′ = 0 L r - 1 h l r  - j2π kl ′ / N ) α k d k  j2π kn / N + 1 N ∑ k = 0 N - 1 ( ∑ l = 0 L d - 1 h l d  - j2π kl / N ) α k W k r  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.