The Conditional Metric Merge Algorithm for Maximum Likelihood Multiuser-Macrodiversity Detection

Abstract—The combination of macrodiversity reception with maximum likelihood (ML) multiuser detection has the capability to reduce thebiterrorrate(BER)formanyusersbyseveralordersofmagnitude compared with multiuser detectors that operate on each antenna separately [1]. In this paper, we present the Conditional Metric Merge (CMM) algorithm which reduces the computational complexity of the ML multiuser-macrodiversity detector by an enormous factor. The CMM algorithm can be viewed as a spatial variant of the Viterbi algorithm. It is a new algorithm and is the ¿rstofitskindasMLmultiusermacrodiversity detection (MUMD) is a relatively new area of research. I