ML CFO and PO Estimation in DCT OFDM Systems under Non-Circular Transmissions

Abstract

Abstract-Frequency synchronization is one of the most important components in orthogonal frequency-division multiplexing (OFDM) systems. Recently, the discrete cosine transform (DCT) based OFDM system has received wide attentions due to several advantages. Hence, the study of frequency synchronization issue for this newly raised system is well on its time. To provide a thorough study, we consider the non-circular transmissions, and the results can be easily generated to circular transmissions if the elliptic variance is set to zero. We present three joint maximum likelihood (ML) carrier frequency offset (CFO) and phase offset (PO) estimators. From both the theoretical analysis and the numerical comparisons, we found new advantages of the DCT-OFDM over the traditional discrete Fourier transform (DFT) based OFDM. These advantages, as well as those already studied in the early works on DCT-OFDM, support the belief that the DCT-OFDM is a new promising multi-carrier modulation (MCM) scheme.

Improved ACLR by Cancellation Carrier Insertion in GFDM Based Cognitive Radios

“…In presence of carrier frequency offsets, the orthogonal subcarriers of OFDM are extremely vulnerable to interference and makes the entire OFDM system very sensitive. OFDM with rectangular pulse shaping has quite high out of band leakage which makes it unsuitable for cognitive radio applications in fragmented white space applications and the requirement for a cyclic prefix limits its spectral efficiency [3]. New multicarrier schemes are being investigated and among them filter bank multicarrier (FBMC) [4], [5] is extremely popular.…”