Impact of out-of-cell interference on strongest-users-only CDMA detectors

A randomly spread direct sequence code division multiple access (DS-CDMA) multi-cell system operating in flat fading is considered. The model adheres to A.D. Wyner\´s infinite linear cell-array setting (see IEEE Trans. Inform. Theory, vol.40, p.1713-27, 1994), where only adjacent-cell interference is present, and characterized by a single parameter, 0≤α≤1. Users are assumed to employ equal rates and transmit powers. The receiver ranks the intracell users according to their received powers, and decodes only the subset that can be reliably decoded. Confining the discussion to asymptotic analysis (in terms of number of users and processing gain), we study four multiuser detection strategies, differing in the amount and type of information available to the receiver with respect to (both intracell and out-of-cell) interfering users. The total capacities under outage constraint, derived as functions of the fraction of users that cannot be reliably decoded (equivalent to the "outage probability"), are analyzed and compared.