Weighted Gram Bigenvalue Characterization of Sum Capacity of Overloaded S-CDMA
Paul Cotae · 2006
By using a Gramian matrix approach and majorization theory, a complete eigenspaces characterization of those sequences which maximize the sum capacity of the single cell overloaded S-CDMA is given. The main result of this paper is a procedure of testing the eigenvalues of the weighted Gram matrix associated to spreading signature in order to characterize the sum capacity. In contrast to the previous results, we prove that the sum capacity of overloaded S-CDMA systems is maximized when all users belong to only one eigenspace: the linear dependent one. Illustrative numerical examples are provided to support our analysis.