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正交频分复用(OFDM)调制技术由于具有良好的抗多径干扰能力和高效的频谱利用率,在许多数字传输系统中被广泛应用,成为当今卫星通信研究的热点。本文提出了基于局部三角变换(LTT)的OFDM系统模型,该系统带外频率谱密度下降快,并能保持相邻的OFDM符号的正交性。给出了用离散余弦变换(DCT)实现的快速算法及复杂度,并考查了最优基的选取。仿真和分析结果表明:该系统误码率比基于快速傅里叶变换(FFT)的系统更小,能更好地适应高速传输带来的大多普勒频移,更有效地利用带宽,为接收端对高速数据的解调提供很好的保证。
Orthogonal Frequency Division Multiplexing (OFDM) modulation technology is widely used in many digital transmission systems due to its good ability of resisting multipath interference and efficient spectrum utilization, and has become a hot research topic in satellite communications today. In this paper, an OFDM system model based on local trigonometry transform (LTT) is proposed, in which the out-of-band frequency spectral density decreases rapidly and the orthogonality of adjacent OFDM symbols can be maintained. The fast algorithm and complexity realized by discrete cosine transform (DCT) are given, and the selection of the optimal basis is examined. The simulation and analysis results show that the BER of the system is smaller than that based on Fast Fourier Transform (FFT), which can better adapt to large Doppler shift caused by high-speed transmission, make more efficient use of bandwidth, End to high-speed data demodulation provides a good guarantee.