Analog Joint Source-Channel Coding for OFDM systems

Recently, analog Joint Source-Channel Coding (JSCC) has been shown to approach the optimal distortion-cost trade-off when transmitting over AWGN channels. In this work we consider analog JSCC over frequency-selective channels using Orthogonal Frequency Division Multiplexing (OFDM) modulation. Due to its high complexity, optimal MMSE analog JSCC decoding is infeasible in OFDM, hence a practical two-stage decoding approach made up of a MMSE estimator followed by a Maximum Likelihood (ML) decoder is proposed. Three different alternatives for system optimization are considered: non-adaptive coding, adaptive coding, and adaptive coding with precoding. We show that the three analog JSCC transmission strategies approach the optimal distortion-cost trade-off although much better performance is obtained with the adaptive coding with precoding method, specially in Multiple Input Multiple Output (MIMO) OFDM systems.