A blind adaptive array for cancellation of strong interference and jamming in DS/CDMA networks

Wireless communication networks employing DS/CDMA schemes have recently become very popular in the commercial sector and have distinct advantages in a military environment as well. Use of adaptive antenna arrays at the base-station currently under consideration for third generation (3G) commercial systems will provide increased capacity as well as higher quality of service (QoS) for its users. Numerous blind adaptive beamforming algorithms have been proposed, however these algorithms are often susceptible to very strong interference which can cause a total loss of the user-to-base-station uplink. Although a large volume of research has been done in the area of narrow-band interference cancellation in DS/CDMA networks, very few authors have dealt with the problem of very strong broadband interference. In this thesis, we develop a blind adaptive replica generation and cancellation (RGC) algorithm that quickly finds the angle of arrival (AOA) of a jammer's dominant signal path, forms a beam in that direction, filters the output of that beamformer with an adaptive tapped delay line filter at each antenna element to capture the multipath signal information, and then subtracts the generated replica signals from each of the antenna elements, thereby cancelling the multipath jamming signal. A mathematical model of the RGC system is developed and an extensive Monte Carlo simulation is used to obtain results. The proposed approach demonstrates an ability to effectively cancel a broadband multipath noise jammer that has a signal power approaching 50 dB greater than a user's received chip power.