Some alternatives in transform-domain suppression of narrow-band interference for signal detection and demodulation

Abstract

Conventional detection and demodulation rules are not ideally suited for use with discrete Fourier transform (DFT) based narrow-band interference suppression, if the DFT incorporates time-weighting to localize the interference spectrally. Detection rules which are adapted to the time-weighting are introduced here and shown to o er signi cant improvements in performance, but their implementation is complex. It is found that if a spectrally-contained orthogonal transform (SCOT) is employed in place of the windowed DFT however, the conventional detection rules have a level of performance comparable to that obtained with DFT based suppression and the adapted rules. In addition to yielding good interference localization, SCOTs bene t from the fact that they provide a Karhunen-Loeve like transform for each component of the observation. The primary focus of the paper is the application of interference suppression for the detection of the presence of covert signals; however, it is also demonstrated that SCOT based suppression is potentially better suited than DFT based suppression for data demodulation in commercial code-division multipleaccess (CDMA) network overlays.

Study on interference suppression based on joint fractional Fourier domain and time domain

“…In strong interference situation, first make a statistical mean, choosing 1 (3,4)  P to complete the process of weakening strong interference, then make a statistic mean of processed signal, choosing 2 (2,3)  P to suppress interference and remove residual interference energy. Specific procedures are as follows:…”

“…Transform domain suppression technology, mainly based on Fast Fourier Transform (FFT), is easy to implement in engineering, effective in narrowband interference and has been widely used [2,3,13]. Transform domain suppression technology is mainly composed of transformation basis selection, interference detection threshold criteria and notch suppression.…”

“…Take the receivers of spread spectrum station, global positioning system (GPS), BeiDou navigation satellite system (BD), constellation satellite system for example, none of them can work normally in strong interference situation. Although the method of suppressing strong narrowband interference is mature at present [1][2][3], it is not effective for suppressing unstable broadband interference in practice.…”

Waveform and Transceiver Designs for Smart Radio

“…More recent research efforts have focused on the further development and analysis of transform domain excision schemes based on filter banks and subband transforms [42], [52]. In particular, in [42], modulated and extended lapped transforms were implemented using cosine-modulated filter banks and analyzed in terms of BER performance; similar analysis was also presented for excision schemes using conventional block transforms.…”

“…It was demonstrated therein that with only modest increases in complexity, lapped transforms may be used to suppress narrowband interferers with significant improvement in BER performance as compared to conventional block transform excision schemes. In [52] Sandberg, et. al.…”