Adaptive filtering and its applications in satellite communications

Article type: Research Article

Authors: Shamma, Mohammed A.

Affiliations: 2591 Ashurst Road, University Heights, OH 44118, USA Tel.: 216 397 0226; E‐mail: mohammed.a.shamma@grc.nasa.gov

Abstract: Adaptive filters have been used in many diverse applications in the past. An investigation of possible applications in space communications to fixed and mobile platforms is addressed here. Mobile satellite communications has been advanced over the past few years with introduction of several new operational systems (e.g., Thuraya, Globalstar, and Irridium), in addition to the existing INMARSAT and Mobile Satellite Ventures systems. In particular, satellite communications with aircraft are currently receiving considerable development attention. With the potentially large number of users, many issues require attention, particularly interference mitigation for improving signal quality. In this paper, stochastic gradient algorithms, based on the Least Mean Square (LMS) algorithm, and Transform based LMS are used in illustrative applications. The type of algorithm chosen affects both the speed of convergence and the complexity of implementation. Several simulation results are provided using models built to study these applications. Among these applications are channel identification, adaptive channel equalization, interference rejection of narrow band signals within wide band signals, and phased array antenna beam forming.

Journal: Space Communications, vol. 19, no. 2, pp. 109-117, 2003