Military Technical College. Cairo, Egypt. AbstractâThis paper investigates the impact of multiple narrow-band interference (NBI) signals or jamming signals.
Blind Adaptive Signal Reception for MC-CDMA Systems in Rayleigh Fading Channels under multiple narrow-band interference signals Mohamed Samir, Ehab M. Shaheen and Ahmed Abd El Tawab Department of Electronic Warfare Military Technical College Cairo, Egypt
Abstract—This paper investigates the impact of multiple narrow-band interference (NBI) signals or jamming signals on the signal reception of multi-carrier code-division multipleaccess (MC-CDMA) systems in single path Rayleigh fading channels. Different blind adaptive algorithms are proposed which determine a weight vector that optimally combines the desired signal contributions from different carriers while suppressing noise and interference. A performance comparison among these algorithms is provided via extensive simulations. No knowledge of the channel conditions (fading coefficients, signature sequences and timing of interferers, statistics of other noises, etc.) nor any training sequence is required. Performance results show that the proposed algorithms perform well and are robust against jamming or NBI.
(AWGN). In such case, not only does it become more difficult to estimate the fading coefficients, but to achieve an optimal reception the statistics of the interference and the noise also have to be estimated. In [1] a blind adaptive receiver has been proposed for DS systems. This method can be viewed as a form of minimum mean-squared error (MMSE) multi-user detection in the frequency domain and proved its robustness against MAI and single NBI signal. Whereas in [2] . This paper proposes an enhancement for the blind adaptive algorithm suggested in [1] in Rayleigh flat fading channels under the impact of multiple NBI signals and the presence of MAI. Such proposed algorithm determines a weight vector which optimally combines the contributions from different carriers and maximizes the signal-to-noise and interference ratio (SNIR). The desired signal contributions are constructively combined, while noise and interference are suppressed. Neither a prior knowledge of the fading coefficients such as the signature sequences, the timing of the interferers and the statistics of other noise nor a training sequence is assumed or required. The paper is organized as follows. The system model is shown in section II. In section III an explanation to the basic blind adaptive technique algorithm suggested in [1] is presented. The stochastic gradient only algorithm is presented in section IV. Section V presents the proposed algorithm which is based on a combination between the basic algorithm suggested in [1] and the stochastic gradient algorithm in order to enhance the system’s capability against NBI. Section V. presents representative simulation results of these various proposed algorithms and finally, section VI draws the conclusions. II. S YSTEM M ODEL Assuming the presence of simultaneous K users, which use the same M carriers in the system. The k th user, for 1