Interference mitigation in WLAN networks using client-based smart antennas

This paper addresses the design and simulation of a smart antenna system for IEEE 802.11b WLAN cards. A two-element array is driven by ferroelectric phase shifters to achieve a 180° scanning range. The phase shifter in the beamforming network (BFN) occupies an area of less than 5.3 mm×5.7 mm. This miniature low cost BFN allows for rejection of interfering signals down to the sidelobe level if the angles of arrival differ. Simulations are conducted using the geometrically based single bounced elliptical model (GBSBEM) method. The results show that on average, up to 4 dB improvement in the C/I ratio of the received signal is achieved in sparse scattering environments (10 or less). This improvement includes the loss of the BFN. As the number of scatterers in the propagation channel increases beyond 20, the receive C/I ratio degrades to that of an isotropic antenna.