Does relay of corrupted packets increase capacity?

Cross-layer protocols that are designed for wireless exhibit both errors and erasures. The nature of these error/erasure impairments and their impact on capacity is a function of the particular cross-layer scheme used. In this paper, we consider two (rather abstract) communication schemes, cross layer design (CLD) and cross layer design with side-information (CLDS). We make a comparative analysis of the channel capacities of these schemes over single and multi-hop wireless channels to identify the conditions under which the cross-layer protocols/channels can provide improved performance over traditional (pure) erasure channels. We show that cross-layer schemes like CLD lead to a capacity increase in most realistic channel scenarios (especially over a single hop) and schemes such as CLDS always lead to a capacity increase.