Spectral efficiency and energy efficiency are two important performance indicators of satellite systems. The Quasi-Constant Envelope Orthogonal Frequency Division Multiplexing(QCE-OFDM) technique can achieve both high...Spectral efficiency and energy efficiency are two important performance indicators of satellite systems. The Quasi-Constant Envelope Orthogonal Frequency Division Multiplexing(QCE-OFDM) technique can achieve both high spectral efficiency and low peak-to-average power ratio(PAPR). Therefore, the QCE-OFDM technique is considered as a promising candidate multi-carrier technique for satellite systems. However, the Doppler effect will cause the carrier frequency offset(CFO), and the non-ideal oscillator will cause the carrier phase offset(CPO) in satellite systems. The CFO and CPO will further result in the bit-error-rate(BER) performance degradation. Hence, it is important to estimate and compensate the CFO and CPO. This paper analyzes the effects of both CFO and CPO in QCE-OFDM satellite systems. Furthermore, we propose a joint CFO and CPO estimation method based on the pilot symbols in the frequency domain. In addition, the optimal pilot symbol structure with different pilot overheads is designed according to the minimum Cramer-Rao bound(CRB) criterion. Simulation results show that the estimation accuracy of the proposed method is close to the CRB.展开更多
A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that...A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.展开更多
基金supported by the National Natural Science Foundation of China(No.91438114,No.61372111 and No.61601045)
文摘Spectral efficiency and energy efficiency are two important performance indicators of satellite systems. The Quasi-Constant Envelope Orthogonal Frequency Division Multiplexing(QCE-OFDM) technique can achieve both high spectral efficiency and low peak-to-average power ratio(PAPR). Therefore, the QCE-OFDM technique is considered as a promising candidate multi-carrier technique for satellite systems. However, the Doppler effect will cause the carrier frequency offset(CFO), and the non-ideal oscillator will cause the carrier phase offset(CPO) in satellite systems. The CFO and CPO will further result in the bit-error-rate(BER) performance degradation. Hence, it is important to estimate and compensate the CFO and CPO. This paper analyzes the effects of both CFO and CPO in QCE-OFDM satellite systems. Furthermore, we propose a joint CFO and CPO estimation method based on the pilot symbols in the frequency domain. In addition, the optimal pilot symbol structure with different pilot overheads is designed according to the minimum Cramer-Rao bound(CRB) criterion. Simulation results show that the estimation accuracy of the proposed method is close to the CRB.
基金supported by the National Natural Science Foundation of China(61571368)
文摘A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.
