Analogue transmission over a two-hop gaussian cascade network

We investigate lossy transmission of two intercorrelated sources over a two-hop cascade network. A low delay analogue based joint source-channel coding scheme is proposed for the case of jointly Gaussian sources over channels with additive white Gaussian noise (AWGN), subject to a quadratic distortion constraint. For the first hop, uncoded transmission is used, with an optimal minimum mean-squared error (MMSE) decoder at the relay node that utilizes the other source as side information. For the second hop, we first perform decorrelation using Karhunen-Loeve transform, followed by dimension reduction mappings. Simulation results show that relative to the optimal performance theoretically attainable (OPTA), uncoded transmission with the optimal MMSE joint decoder for the first hop is able perform close to OPTA when the inter-correlation is relatively weak. For the second hop, result of the proposed scheme is able to come within 1.5 dB from OPTA.