Title :
Adaptive transform domain interference suppression in a hybrid DS/FH-system
Author :
Pouttu, Ari ; Juntti, Juhani ; Kumpumäki, Timo
Author_Institution :
Telecommun. Lab., Oulu Univ., Finland
Abstract :
We study the performance of a hybrid direct sequence frequency hopping (DS/FH) system with interference suppression in an environment where narrowband (relative to the DS spreading code bandwidth) interference perturbs the signal. In suppressing the narrowband interference, a transform domain approach has been chosen, i.e. the interference suppression takes place, e.g. in the frequency domain. This approach is more practical since the duration of a frequency hop is prohibitive to the use of time domain adaptive filtering. The aim of this paper is to study the relative performance of four different adaptive rules used in determining and suppressing the interfered frequencies in the frequency domain. The interference environment changes from frequency hop to hop but during each hop the interference is considered time-invariant. To avoid spectral leaking of the interfering power, windowing can be performed prior to transformation. The transformations are accomplished with the FFT and the inverse FFT algorithms. After the interference suppression the signal is transformed back to the time domain to be fed to the DS-code matched filter. The criterion used for the performance comparisons is the bit error probability as a function of E1/N0 and S/J. The numerical results were obtained by Monte Carlo simulations
Keywords :
adaptive filters; error statistics; fast Fourier transforms; frequency hop communication; frequency-domain analysis; interference suppression; matched filters; spread spectrum communication; DS-code matched filter; Monte Carlo simulations; adaptive transform domain; bit error probability; frequency domain; hybrid DS/FH system; hybrid direct sequence frequency hopping system; interference suppression; inverse FFT algorithms; narrowband interference; numerical results; spreading code bandwidth; time domain; time-invariant interference; Additive white noise; Demodulation; Frequency; Gaussian noise; Interference suppression; Matched filters; Narrowband; Signal generators; Spread spectrum communication; Time factors;
Conference_Titel :
Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on
Conference_Location :
Sun City
Print_ISBN :
0-7803-4281-X
DOI :
10.1109/ISSSTA.1998.726256