Random sequence multisets for synchronous code-division multiple-access channels

The effect of using randomly selected sequence multisets for the uplink of a synchronous code-division multiple-access channel is considered. A tight lower bound on the expected value of the sum capacity over the ensemble of randomly selected sequence multisets is given. For large systems, the sum r ate penalty for using randomly selected multisets is shown to be at most 1 nat and to vanish as the number of users becomes large, compared to the seq uence length.