Diversity Combining of OFDM for Aeronautical Channels

Abstract

This paper presents the design and performance of an Orthogonal Frequency Division Multiplexing (OFDM) scheme with the incorporation of diversity combining. This work takes advantage of the unique properties of the two-ray channel that dominates aeronautical telemetry. Such channels are characterized by deep nulls in the channel which depends on the difference in the differential delay of the paths. The diversity scheme takes advantage of this property to combine multiple antenna channels which are offset in space such that the nulls appear at different frequencies. An optimum combining scheme is developed which enables enhanced performance on 3-dB SNR channels.