In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal proce...In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.展开更多
Traditional pulse Doppler radar estimates the Doppler frequency by taking advantage of Doppler modulation over different pulses and usually it requires a few pulses to estimate the Dop- pler frequency. In this paper, ...Traditional pulse Doppler radar estimates the Doppler frequency by taking advantage of Doppler modulation over different pulses and usually it requires a few pulses to estimate the Dop- pler frequency. In this paper, a novel range-Doppler imaging algorithm based on single pulse with orthogonal frequency division multiplexing （OFDM） radar is proposed, where the OFDM pulse is composed of phase coded symbols. The Doppler frequency is estimated using one single pulse by utilizing Doppler modulation over different symbols, which remarkably increases the data update rate. Besides, it is shown that the range and Doppler estimations are completely independent and the well-known range-Doppler coupling effect does not exist. The effects of target movement on the performances of the proposed algorithm are also discussed and the results show that the algo- rithm is not sensitive to velocity. Performances of the proposed algorithm as well as comparisons with other range-Doppler algorithms are demonstrated via simulation experiments.展开更多
In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiple...In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiplexing （MIMO- OFDM） systems. It exploits multiple antennas and subblocks to provide additional degrees of freedom to benefit the system. To reduce the implementation complexity of the proposed scheme, two simple suboptimal schemes are further presented based on the minimum current maximum criterion; one adopts sequential search and the other employs random binary grouping. The simulation results exhibit the effectiveness of these proposed schemes.展开更多
基金supported by the NNSF of China(No.61177071, No.61250018)the Key Program of Shanghai Science and Technology Association (12dz1143000)
文摘In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.
基金supported by the National Natural Science Foundation of China(No.61401475)
文摘Traditional pulse Doppler radar estimates the Doppler frequency by taking advantage of Doppler modulation over different pulses and usually it requires a few pulses to estimate the Dop- pler frequency. In this paper, a novel range-Doppler imaging algorithm based on single pulse with orthogonal frequency division multiplexing （OFDM） radar is proposed, where the OFDM pulse is composed of phase coded symbols. The Doppler frequency is estimated using one single pulse by utilizing Doppler modulation over different symbols, which remarkably increases the data update rate. Besides, it is shown that the range and Doppler estimations are completely independent and the well-known range-Doppler coupling effect does not exist. The effects of target movement on the performances of the proposed algorithm are also discussed and the results show that the algo- rithm is not sensitive to velocity. Performances of the proposed algorithm as well as comparisons with other range-Doppler algorithms are demonstrated via simulation experiments.
基金the National Natural Science Foundation of China（NSFC 60496312）；the Hi-Tech Research and Development Program of China（2006AA01Z260）；KDDI company of Japan.
文摘In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiplexing （MIMO- OFDM） systems. It exploits multiple antennas and subblocks to provide additional degrees of freedom to benefit the system. To reduce the implementation complexity of the proposed scheme, two simple suboptimal schemes are further presented based on the minimum current maximum criterion; one adopts sequential search and the other employs random binary grouping. The simulation results exhibit the effectiveness of these proposed schemes.
