Performance of Turbo Coded OFDM Modulation over an Aeronautical Channel

Abstract

The main objectives of Integrated Network Enhanced Telemetry (iNET) are increased data rate and improved spectral efficiency. In this paper we propose the transmission scheme for the physical layer to be coded Quadrature Amplitude Modulation-Orthogonal Frequency Division Multiplexing (QAM OFDM) which enables high data rates and spectrum efficiency. However in high mobility scenarios, the channel is time-varying the receiver design is more challenging. In this paper pilot-assisted channel estimation is used at the receiver, with turbo coding to enhance the performance; while the effect of inter symbol interference (ISI) is mitigated by cyclic prefix. The focus of this paper is to evaluate the performance of OFDM with QAM over an aeronautical channel. The M-QAM with OFDM provides a higher data rate than QPSK hence it is chosen in this paper. The implementation is done using Inverse Fast Fourier Transform (IFFT) and the Fast Fourier Transform (FFT). This paper considers how the performance of Coded QAM OFDM can be enhanced using equalization to compensate for inter symbol interference, and using turbo coding for error correction.