Analytic cascaded filterbanks for multicarrier modulation

摘要

Filterbank multicarrier has been proposed as an alternative to rthogonal frequency division multiplexing (OFDM). A uniform Discrete Fourier Transform (DFT) transmultiplexer cannot have maximum packing efficiency while using slowly decaying pulses. Maximally decimated filterbanks and transmultiplexers can be used interchangeably. Designing a filterbank with large number of independent filters can be a tedious job. So, wavelet packets have been tried as a basis for multicarrier modulation. However, real wavelet packets have energy on both sides of the spectrum, making the use of a single tap equalisation and usage of water-filling algorithm difficult. The authors propose a cascade of filterbanks which produce nearly analytic waveforms. They also design a class of 3-band filterbanks whose high-pass filters are structurally complex conjugate pairs, which reduce the complexity of the design. A 5-band filterbank is also designed with similar properties and a hybrid cascade of filterbanks is also investigated. The performance of the cascade and hybrid cascade through a wireless channel is compared with OFDM without cyclic prefix and Daubechies wavelet packets. In highly frequency selective channels, the proposed cascaded filterbank design outperforms OFDM without cyclic prefix and Daubechies wavelet packets in terms of error rate.