I. Introduction
Using training sequences in the frame header for synchronization is one of the most important synchronization schemes in Orthogonal Frequency Division Multiplex (OFDM) transmission. Compared to the schemes with pilot or cyclic prefix aided, the training sequence can provide higher accuracy even if there is a carrier frequency error in receiving. In the OFDM transmission, duplicated sequences are often utilized to form the symbol for the synchronization. Meanwhile, Schmidl&Cox training sequence has two identical parts, i.e., [1]. Minn sequence comprises four parts in length of as [2], where denotes the length of sequence. Park sequence is also approximately divided into four parts as , where and are the conjugates of and [3]. Additionally, is symmentric to . In the above three synchronization schemes, the timing metric is defined as M\left (d \right) = {{{{\left\vert {P\left (d \right)} \right\vert}^2}} \over {{{\left ({R\left (d \right)} \right)}^2}}}\eqno{\hbox{(1)}}