A Flexible Transmit Diversity Assisted Broadband Multicarrier DS-CDMA Scheme

In this contribution we identify some of the key problems that may be encountered when designing a broadband multiple-access -systems having bandwidth on the order of tens or even hundreds MHz We commence with a comparative discussion in terms of the Characteristics of three typical code-division multiple-access- (CDMA) schemes, namely single-carrier direct-sequence CDMA (SC DS-CDMA), multicarrier CDMA (MC-CDMA) and multicarrier (MC DS-CDMA). Their benefits and deficiencies are analyzed, when aiming for supporting ubiquitous communications over a variety of channels encountered in indoor, open rural, suburban and urban environments. We also consider space-time spreading (ST'S) assisted broadband MC DS-CDMA and discuss s system architecture, its achievable capacity improvement and the system performance attained