编码正交频分复用(Coded orthogonal frequency division multiplexing,COFDM)是一种多载波数字通信调制技术,它具有频谱利用率高和可对抗多径时延扩展等特点。文章介绍了COFDM技术的基本原理,对基于该技术的无线视频传输系统在海上视...编码正交频分复用(Coded orthogonal frequency division multiplexing,COFDM)是一种多载波数字通信调制技术,它具有频谱利用率高和可对抗多径时延扩展等特点。文章介绍了COFDM技术的基本原理,对基于该技术的无线视频传输系统在海上视频传输的实际应用进行了分析论述。展开更多
In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing(BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effe...In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing(BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR(signal-to-noise ratio) mapping(EESM) with the maximum a posteriori(MAP) algorithm, a bit LLR(log-likelihood ratio) wise EESM(BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding(AMC) procedure, bringing about throughput improvement at low hardware cost.展开更多
文摘基于编码正交频分复用的数字音频广播(DAB)具有鲁棒性高和激光唱盘(CD)音质等优良性能。带内同频道(IBOC)制式的DAB能够在已有的模拟广播频道内同播模拟和数字两种信号,完全兼容现有的模拟接收机,以较低成本实现向全数字化 DAB的平滑过渡。作者论述了 FM IBOC DAB的频谱分析,综述了混合模式 FM IBOC DAB的发射(接收)机的基本结构和感知音频编码、前向纠错编码、OFDM、第一邻频道干扰消除、时间延迟分集和音频混合等关键技术,提出了发展我国的 IBOC DAB的一些建议。
文摘编码正交频分复用(Coded orthogonal frequency division multiplexing,COFDM)是一种多载波数字通信调制技术,它具有频谱利用率高和可对抗多径时延扩展等特点。文章介绍了COFDM技术的基本原理,对基于该技术的无线视频传输系统在海上视频传输的实际应用进行了分析论述。
基金the Shanghai Basic Research KeyProject(No.11DZ1500206)the NationalScience and Technology Major Project of China(No.2012ZX03001013-003)
文摘In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing(BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR(signal-to-noise ratio) mapping(EESM) with the maximum a posteriori(MAP) algorithm, a bit LLR(log-likelihood ratio) wise EESM(BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding(AMC) procedure, bringing about throughput improvement at low hardware cost.
