  This paper investigates the joint source-channel coding problem of sending a
memoryless source over a memoryless broadcast channel. An inner bound and
several outer bounds on the admissible distortion region are derived, which
respectively generalize and unify several existing bounds. As a consequence, we
also obtain an inner bound and an outer bound for the degraded broadcast
channel case. When specialized to the Gaussian or binary source broadcast, the
inner bound and outer bound not only recover the best known inner bound and
outer bound in the literature, but also generate some new results. Besides, we
also extend the inner bound and outer bounds to the Wyner-Ziv source broadcast
problem, i.e., source broadcast with side information available at decoders.
Some new bounds are obtained when specialized to the Wyner-Ziv Gaussian and
Wyner-Ziv binary cases.
