Patent ID: 7529319

Claim:
A speed estimation method, for detecting relative speed of a transmitter and a receiver transmitting symbols by OFDM sub-carriers through a channel, comprising: establishing a first correlation table indicating first conceptual relationships between relative speeds and channel characteristics based on Doppler shift theory and a first delay factor; establishing a second correlation table indicating second conceptual relationships between relative speeds and channel characteristics based on Doppler shift theory and a second delay factor; wherein the second conceptual relationships present a lesser scale and a higher distinguish ability than that of the first conceptual relationships; estimating a first channel characteristic based on the first delay factor caused by the a relative movement of the transmitter and the receiver; looking up the first correlation table to determine the relative speed according to the first channel characteristic; and if the first channel characteristic is lower than a least item in the first correlation table, estimating a second channel characteristic based on the second delay factor and looking up the second correlation table based on the second channel characteristic to determine the relative speed.