Multipath chirp signal detection based on biorthogonal fourier transform

The multiple-chirp-rate signal has been proved a good orthogonal characteristic in BFT (biorthogonal Fourier transform) domain. In this work, it is adopted to improve the modulation efficiency with BFT demodulator. However, the performance of BFT demodulator in real wireless environment was not evaluated yet. By our derivation, unfortunately, the orthogonality of multiple-chirp-rate chirp in BFT domain is proved to be damaged over multipath channel. Furthermore, the interference model is constructed, and the linear MMSE detection is proposed to recover the M-ary symbols. Numerical results indicate that the algorithm can simultaneously mitigate the inter-symbol interference (ISI) and the inter-rate interference of the BFT output in multipath environments.