Union bound of maximum likelihood detection in downlink MIMO MC-CDMA systems

This paper derives a tight union bound on the symbol error probability of maximum likelihood detection (MLD) in downlink multiple-input-multiple-output (MIMO) multicarrier code division multiple access (MC-CDMA) systems. The analysis is performed in multiuser and frequency-selective fading environments. The bound of MLD is used to demonstrate the optimum performance of MIMO MC-CDMA systems with respect to the number of users, subcarriers and antennas.