Abstract

ADAPTIVE ANTENNA ARRAYS FOR SATELLITE PERSONAL COMMUNICATION SYSTEMS by Keng-Jin Lian Committee Chairman: Timothy Pratt Department of Electrical Engineering ABSTRACT Since about the turn of the decade, several proposals have come forth for personal communication services implemented by means of multiple satellite systems. These satellite systems are similar to current terrestrial cellular technologies, which are still relatively new and have numerous technical problems associated with them. As a result, these satellite systems will also experience some of the similar problems. Two of such problems are the issue of multipath and interference. These problems may result in significant link degradation and affect overall capacity. To overcome this problem, adaptive antenna arrays on handheld terminals are proposed. This technique is believed to be better than omni-directional antennas which radiate in all directions. Adaptive antenna arrays have the ability to adapt to the changing environment and null out the interference. The LMS algorithm was investigated and used in the simulation of the adaptive array. The performance of the LMS array was discussed in detail. In the case of a multipath, an alternate approach was proposed where a diversity combiner is used to phase shift the multipath and combine the Signal of Interest and multipaths constructively.

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