Adaptive signal processing for low Earth orbit satellite communications

Small link margins, multipath fading and human body effects degrade the performance of low Earth orbit satellite (LEOS) handheld terminals. Adaptive antennas take the rapidly changing environment and human body influence into account to maximise the final signal to interference plus noise ratio (STNR). The proposed reception system for LEOS handsets is an adaptive antenna system with an electric field antenna and a magnetic loop antenna. By using the electric field and magnetic field antennas, zero correlation can be provided. Equal gain combining is not suitable for handsets, since it is too sensitive to the signal angle of arrival. Only the best case of equal gain combining is used as a comparison with an adaptive antenna system. The worst case of an adaptive antenna system may provide lower bit error rate (BER) than the best case of equal gain combining, since the adaptive antenna further improves the performance by nullification of interference