The Sum-Capacity of Discrete-Noise Multiple-Access Channels With Single-User Decoding and Identical Codebooks

The authors consider an additive multiple-access channel model where all users are constrained to use identical codebooks, and where single-user decoding is performed at the receiver. They study the sum-capacity of the channel for an arbitrarily large, but finite, number of users. For a noiseless n-user channel, they construct a signaling scheme that achieves rates per user that are arbitrarily large, proving that the sum-capacity is infinite, whether the users are average and/or peak power limited or not.