数字通信中基于双正交子波的波形成形

Waveform coding of digital symbols based on biorthogonal wavelets

讨论了数字调制技术中的波形成形问题,提出利用双正交子波实现波形成形的思想.与正交子波相比,双正交子波具有设计灵活、自由度大的特点.证明了利用双正交子波实现波形成形满足Nyquist准则;研究了利用双正交子波进行基带成形的具体数字化所涉及的问题,并在频谱利用率和误码性能两个方面进行了对比分析,给出了计算机模拟结果,得到了与理论分析一致的结论:利用双正交子波实现波形成形可以获得高的频谱利用率,但功率有效性降低,适合某些特定的通信场合.

This paper discusses the technique of waveform coding for digital modulation and presents the idea of waveform coding based on biorthogonal wavelets. In contrast with orthogonal wavelets, biorthogonal wavelets have the advantages of flexible design and large freeness. From the signals time frequency property, the gausian function is an ideal choice within the limit of uncertainty principles. But it does not meet the Nyquist criteria. This paper uses the biorthogonal scale function as a baseband waveform to approximate the gausian function for obtaining the good time frequency property. Firstly, it is shown that waveform coding based on biorthogonal wavelets meets the Nyquist criteria. Then, some related problems to digital implementation are investigated. Compared with waveform coding using orthogonal wavelets, the results of performance analysis of spectrum and power efficiency on waveform coding based on biorthogonal wavelets are given. The conclusions drawn from computer simulation agree with theorotical analysis: waveform coding based on biorthogonal wavelets can obtain high spectrum efficiency at a cost of slightly reduced power efficiency and be applicable to some specific communication situations.