Lossy Source Coding with Broadcast Side Information
Yiqi Chen, Holger Boche, Marc Geitz
TL;DR
This work analyzes lossy source coding with broadcast side information where a helper observing a correlated source communicates over a degraded broadcast channel to two receivers. It develops outer and inner bounds for the rate-distortion-bandwidth region and provides separation-based inner bounds with explicit auxiliary-variable characterizations, including special cases where the separation scheme is optimal. A Gaussian example with ρ=1 contrasts the separation-based approach against uncoded schemes, identifying regimes where each strategy is advantageous and deriving corresponding rate-distortion expressions. The results illuminate when joint source-channel coding with a helper is necessary versus when a separation-based approach suffices, with implications for multi-user JSCC design under broadcast constraints. Overall, the paper extends existing single-receiver and degraded-side-information results to a two-receiver broadcast setting with a helper, offering both general outer bounds and tractable special cases, including a detailed quadratic Gaussian analysis.
Abstract
This paper considers the source coding problem with broadcast side information. The side information is sent to two receivers through a noisy broadcast channel. We provide an outer bound of the rate--distortion--bandwidth (RDB) quadruples and achievable RDB quadruples when the helper uses a separation-based scheme. Some special cases with full characterization are also provided. We then compare the separation-based scheme with the uncoded scheme in the quadratic Gaussian case.
