APBT-Based Channel Estimation for OFDM System

—Orthogonal Frequency Division Multiplexing (OFDM) has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL Internet access, wireless networks, powerline networks, and 4G mobile communications. It plays an important role in the new generation of mobile communication. In OFDM system, channel estimation is a necessary technique for improving the system’s accuracy at the receiving end. Therefore channel estimation based on pilot assistant has been a hot area of research for several years. Recently, the advantages of the Discrete Cosine Transform (DCT) based channel estimation have come to light. Compared to channel estimation based on Discrete Fourier Transform (DFT), DCT-based channel estimation could improve the performance of channel estimation, and it is also an efficient way to suppress the Gaussian white noise. A new transform called All Phase Biorthogonal Transform (APBT) was proposed in recent years, APBT has the similar energy compaction property of DCT. Therefore, a novel channel estimation based on APBT was proposed for QPSK and 16-QAM modulated signals in this paper. The proposed method can solve the low leakage problem which exists in DFT-based channel estimation and “error floor” which exists in DCT-based channel estimation. From experimental results, the APBT-based channel estimation provides improved performance in terms of Bit Error Rate (BER) and reduction in the Mean Square Error (MSE) compared to conventional channel estimation based on DFT and DCT.