Mac Aware Coding Strategy for Multiple User Information Embedding

Multiple user information embedding is concerned with embedding several messages into the same host signal. While emphasizing the tight relationship with conventional multiple user information theory, this paper presents several implementable "dirty paper coding" (DPC) based schemes for multiple user information embedding. These are obtained by exploring strong connections with the well-known Gaussian multiple access channel (MAC) with state information at the encoders. Two practical schemes are compared. The first -rather intuitive- consists in a straightforward superimposition of DPC schemes. The second consists in a joint design of these dirty paper coding schemes, based on the ideal DPC-based coding for the equivalent MAC channel. These results extend to the multiple user case the practical implementations (QIM and SCS) that have been originally conceived for one user. Then, we extend the results to a more general coding based on lattice (vector) codebooks, showing that the gap to full performances can be bridged up by using finite dimensional lattice codebooks, at the cost of an increased computational complexity. The improvements brought by a joint design are illustrated by bit error rates curves and achievable rates region