Channel Coding for Multimedia Transmission on High-Speed Flying Devices

Abstract

Communication systems for high-speed flying devices, such as drones and missiles, have performances with error-floor caused by the Doppler effect, which causes inter-carrier interference (ICI) and destroys real-time data transmission. Channel coding cannot reduce error-floors, but channel coding may still achieve performance with turbo-cliff. This paper proposes a broadband communication system for high-speed flying devices using soft 4 quadrature amplitude modulation (4-QAM) modulations with the optimal threshold S for practical implementation assuming that the maximum/minimum log-likelihood ratio (LLR) values of ±709. We use orthogonal frequency division multiplexing (OFDM) with low-density parity-check (LDPC) codes as the channel coding scheme and minimum mean squared error (MMSE) equalization. To reduce the computational complexity and to keep the data rate high, we use only a single pilot for the channel estimation. Computer-based simulations for several high speeds are performed to evaluate the performance of the proposed high-speed flying devices system. The bit error rate (BER) performance is evaluated based on LLR under additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. The results confirmed that the proposed system with the optimal threshold S can avoid unstable jumping error with better turbo-cliff and lower error-floor. The maximum speed the system can achieve for BER of 10 −2 is 400 km/h. The results of this paper are expected to contribute significantly to the development of communication systems on flying devices.