On the distance distribution of CDMA multiuser signal set

The asymptotic efficiency of each user in an asynchronous multiuser CDMA. system is characterized by the user´s associated minimum distance D_k,min. However, computing this quantity is in general, an NP-hard problem. Determining the distance distribution of the signal set in such systems is similarly difficult. We show that the distribution can be approximated by the Nakagami distribution when the channel undergoes quasi-static fading and when the product of the number of users and the number of bits of each user is large. We also provide an efficient algorithm which can compute D_k,min accurately for each user that makes use of a previously proposed multiuser detector