On strongest-users-only detectors for DS-CDMA cellular systems

The fundamental figure of merit that specifies the ultimate performance of cellular systems is the per-cell spectral efficiency. The underlying tacit assumption in previous spectral efficiency analyses is that all active users are (reliably) decoded, regardless of their received powers. Unfortunately, in practice, this assumption may not hold and we consider an alternative approach. Assuming single cell-site processing, four types of multiuser detection strategies are considered: (1) the "conventional" matched-filter detector; (2) the linear MMSE detector; (3) a detector that "optimally" decodes the transmissions of the maximum decodable subset of intra-cell users, referred to as the "single-cell optimum (SCO) detector"; (4) an "optimum" detector referred to as the "single cell-site processing optimum (SCPO) detector". The strategies are analyzed and compared in terms of their outage constrained capacities, analytically derived as functions of the fraction of undecodable users (FUU), equivalent to the outage probability.