This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the p...This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the purpose of accomplishing soft input soft output iterative decoding of LDPC codes, a new soft decision metric generation method is proposed,which obviates the need of the noise variance estimation, for M-PSK/M-QAM-type high-order modulation over frequency selective fading channel. Computer simulation indicates that, there is no performance loss with our new metric, but the complexity of implementation is reduced, and that the LDPC codes are effective to improve the Bit Error Rate (BER) of FMT in frequency selective fading channel.展开更多
The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation a...The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation accuracy degrade. The goal of this paper is to analytically assess this degradation when Carrier Frequency Offset (CFO) and Doppler shift exist jointly. Then the finite-sample Cramer-Rao Lower Bound (CRLB) is derived and close-form asymptotical expression is given for large-sample CRLB. These expressions give insights into the performance room for frequency estimation. Also the variance of Doppler shift estimator is simulated to illustrate the theoretical results.展开更多
The de spreading algorithm of MC 2D CDMA (Multi Carrier 2 Dimension Code Division Multiple Access) uses a simple correlator and complex spread spectrum sequences. Each chip of spreading spectrum sequence is in two sub...The de spreading algorithm of MC 2D CDMA (Multi Carrier 2 Dimension Code Division Multiple Access) uses a simple correlator and complex spread spectrum sequences. Each chip of spreading spectrum sequence is in two sub carriers. With one sub carrier in deep fading, the chip in the other sub carrier would compensate to improve performance. Orthogonal restore correlation (ORC) explained the algorithm. The performance was examined analytically and by computer simulations. The performance is better than that of regular MC 2D CDMA model.展开更多
A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with ...A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with one of the tonal components, and several FSFANC systems can run independently in paralld to cancel the selected multiple tones. The proposed algorithm adopts a simple structure with only two coefficients that can be explained as the real and imaginary parts of the structure to model the secondary path, and estimates the secondary path by injecting sinusoidal identification signals. Theoretical analysis and laboratory experiments show that the proposed algorithm possesses stone advantages, such as simpler structure, less computational burden, greater stability, and fast converging speed.展开更多
The all-phase fast Fourier transform (apFFT) is proposed as a digital demodulation algorithm in place of the fast Fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM) based multiple-input mult...The all-phase fast Fourier transform (apFFT) is proposed as a digital demodulation algorithm in place of the fast Fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM) based multiple-input multiple-output (MIMO) communication systems. The amplitude spectrum of apFFT-demodulated symbols is the square of that of the FFT, which helps reduce the Gaussian noise to a great extent. Moreover, the phases of apFFT symbols are not affected by the frequency shift between the transmitter and receiver oscillators. These properties particularly appeal to MIMO systems over frequency-selective fading channels. The proposed MIMO-OFDM system employing the apFFT is validated using the spatial channel model (SCM) proposed by the third generation partnership project (3GPP). The simulation results demonstrate that the performance of the proposed system after compensating for the rate loss due to zero bits inserted in the space-frequency OFDM (SF-OFDM) coding scheme, still considerably outperforms the conventional system over 3GPP SCM channels, especially under poor channel conditions.展开更多
In this paper, we propose a cooperative anti-interference spectrum sharing strategy with secondary user selection where the secondary system can gain spectrum access along with the primary system. Specifically, second...In this paper, we propose a cooperative anti-interference spectrum sharing strategy with secondary user selection where the secondary system can gain spectrum access along with the primary system. Specifically, secondary user and are selected to transmit the primary and secondary signal through different bandwidth in the second transmission slot which occupies fraction of the time. Thus, the primary and secondary systems will not interfere with each other. We study the joint optimization of time and bandwidth allocation such that the transmission rate of the secondary system is maximized, while guaranteeing the primary system to achieve its target rate. Simulation results confirm efficiency of the proposed spectrum sharing strategy, and the significant performance improvement of the cognitive system.展开更多
基金Supported by 863 program of China under Grant 2001AA123015.
文摘This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the purpose of accomplishing soft input soft output iterative decoding of LDPC codes, a new soft decision metric generation method is proposed,which obviates the need of the noise variance estimation, for M-PSK/M-QAM-type high-order modulation over frequency selective fading channel. Computer simulation indicates that, there is no performance loss with our new metric, but the complexity of implementation is reduced, and that the LDPC codes are effective to improve the Bit Error Rate (BER) of FMT in frequency selective fading channel.
文摘The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation accuracy degrade. The goal of this paper is to analytically assess this degradation when Carrier Frequency Offset (CFO) and Doppler shift exist jointly. Then the finite-sample Cramer-Rao Lower Bound (CRLB) is derived and close-form asymptotical expression is given for large-sample CRLB. These expressions give insights into the performance room for frequency estimation. Also the variance of Doppler shift estimator is simulated to illustrate the theoretical results.
文摘The de spreading algorithm of MC 2D CDMA (Multi Carrier 2 Dimension Code Division Multiple Access) uses a simple correlator and complex spread spectrum sequences. Each chip of spreading spectrum sequence is in two sub carriers. With one sub carrier in deep fading, the chip in the other sub carrier would compensate to improve performance. Orthogonal restore correlation (ORC) explained the algorithm. The performance was examined analytically and by computer simulations. The performance is better than that of regular MC 2D CDMA model.
基金supported by the Independent Innovation Foundation of Shandong University(No.2009JC004)the Natural Science Foundation of Shandong Province(No.Y2007G31)
文摘A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with one of the tonal components, and several FSFANC systems can run independently in paralld to cancel the selected multiple tones. The proposed algorithm adopts a simple structure with only two coefficients that can be explained as the real and imaginary parts of the structure to model the secondary path, and estimates the secondary path by injecting sinusoidal identification signals. Theoretical analysis and laboratory experiments show that the proposed algorithm possesses stone advantages, such as simpler structure, less computational burden, greater stability, and fast converging speed.
基金Supported by National Natural Science Foundation of China (No.60972054)National High-Tech R&D Program ("863"Program) of China(No.2009AA011507)
文摘The all-phase fast Fourier transform (apFFT) is proposed as a digital demodulation algorithm in place of the fast Fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM) based multiple-input multiple-output (MIMO) communication systems. The amplitude spectrum of apFFT-demodulated symbols is the square of that of the FFT, which helps reduce the Gaussian noise to a great extent. Moreover, the phases of apFFT symbols are not affected by the frequency shift between the transmitter and receiver oscillators. These properties particularly appeal to MIMO systems over frequency-selective fading channels. The proposed MIMO-OFDM system employing the apFFT is validated using the spatial channel model (SCM) proposed by the third generation partnership project (3GPP). The simulation results demonstrate that the performance of the proposed system after compensating for the rate loss due to zero bits inserted in the space-frequency OFDM (SF-OFDM) coding scheme, still considerably outperforms the conventional system over 3GPP SCM channels, especially under poor channel conditions.
基金supported by China National Science Foundation under Grand No. 61402416Natural Science Foundation of Zhejiang Province under Grant No. LQ14F010003+1 种基金Natural Science Foundation of Jiangsu Province under Grant No. BK20140828the Scientific Foundation for the Returned Overseas Chinese Scholars of State Education Ministry
文摘In this paper, we propose a cooperative anti-interference spectrum sharing strategy with secondary user selection where the secondary system can gain spectrum access along with the primary system. Specifically, secondary user and are selected to transmit the primary and secondary signal through different bandwidth in the second transmission slot which occupies fraction of the time. Thus, the primary and secondary systems will not interfere with each other. We study the joint optimization of time and bandwidth allocation such that the transmission rate of the secondary system is maximized, while guaranteeing the primary system to achieve its target rate. Simulation results confirm efficiency of the proposed spectrum sharing strategy, and the significant performance improvement of the cognitive system.
