Sum capacity of oversaturated channels based on a hierarchy of orthogonal sets

Some oversatured channels that have been presented in the literature can be seen as hierarchies of orthogonal signature sets. We introduce a framework for oversaturated channels based on a hierarchy of orthogonal sets. The sum capacity under the equal average input energy constraint is found to depend only on the number of users in every orthogonal layer of the hierarchy. In addition to this, m-OCDMA achieves the highest sum capacity among all members of the considered hierarchy for a fixed number of users.