Delay-Distortion-Power Trade Offs in Quasi-Stationary Source Transmission over Block Fading Channels

TL;DR

This paper explores the trade-offs between delay, distortion, and power in transmitting quasi-stationary sources over block fading channels, proposing buffer-based coding schemes with analytical solutions and insights into buffer size effects.

Contribution

It introduces four buffer-aware coding schemes with closed-form solutions for optimizing distortion, rate, and power, and analyzes their performance in high SNR regimes.

Findings

Buffer size impacts performance saturation at high power levels.

Adaptive power schemes outperform fixed rate schemes with limited buffers.

Analytical solutions provide insights into distortion and power trade-offs.

Abstract

This paper investigates delay-distortion-power trade offs in transmission of quasi-stationary sources over block fading channels by studying encoder and decoder buffering techniques to smooth out the source and channel variations. Four source and channel coding schemes that consider buffer and power constraints are presented to minimize the reconstructed source distortion. The first one is a high performance scheme, which benefits from optimized source and channel rate adaptation. In the second scheme, the channel coding rate is fixed and optimized along with transmission power with respect to channel and source variations; hence this scheme enjoys simplicity of implementation. The two last schemes have fixed transmission power with optimized adaptive or fixed channel coding rate. For all the proposed schemes, closed form solutions for mean distortion, optimized rate and power are provided and in the high SNR regime, the mean distortion exponent and the asymptotic mean power gains are derived. The proposed schemes with buffering exploit the diversity due to source and channel variations. Specifically, when the buffer size is limited, fixed channel rate adaptive power scheme outperforms an adaptive rate fixed power scheme. Furthermore, analytical and numerical results demonstrate that with limited buffer size, the system performance in terms of reconstructed signal SNR saturates as transmission power is increased, suggesting that appropriate buffer size selection is important to achieve a desired reconstruction quality.