On the Performance of Serially Concatenated CPM-OFDMA Schemes for Aeronautical Telemetry

In this paper, we investigate the performance of a serially concatenated CPM-OFDM (Continuous Phase Modulation Orthogonal Frequency Division Multiplexing) scheme in various frequency selective fading environments that are typical for aeronautical telemetry. CPM-OFDM is a novel modulation technique that assigns the sampled, complex outputs of a CPM to a set of orthogonal subcarriers for a DFT-precoded OFDM style transmission. This approach maintains much of the power efficiency of CPM while incorporating the spectral efficiency of OFDM. At the receiver, low complexity frequency domain equalization techniques can be applied to mitigate the impact of the radio channel. Although uncoded CPM-OFDMA has been investigated, coded CPM-OFDMA is a new area of focus, which promises to offer good performance in highly dynamic telemetry environments. The serially concatenated code is comprised of an inner code and an outer code. The inner code is generated from the discretetime samples of a PCM-FM modulation while the outer code is derived from a nonrecursive convolutional code. We evaluate the proposed scheme over the additive white Gaussian noise channel as well as in two frequency selective fading environments that are characteristic of aeronautical telemetry.