OFDM Blind Signal Detection Using the Signal Probability Information

In recent years the quadratic program (QP) is applied for the blind signal detection of the time-varying OFDM systems. The minimum solution of the QP could be obtained through the class of the sphere decoder (SD) algorithm, which is equivalent to the tree search approach. In this paper, we derive some formulas describing the probability information about the received signal. With these formulas, a novel mechanism is proposed to sort all the possible candidate values of the tree search orderly. Different from other SD candidate ordering mechanisms, the new mechanism prevents the search from going deep on the wrong subtrees, ensuring that the correct path is found with as least complexity as possible. The simulations prove the effectiveness of the new method.