Gb. Giannakis et al., Load-adaptive MUI/ISI-resilient generalized multi-carrier CDMA with linearand DF receivers, EUR T TELEC, 11(6), 2000, pp. 527-537
A plethora of single-carrier and multi-carrier (MC) CDMA systems have been
proposed recently to mitigate intersymbol interference (ISI) and eliminate
multiuser interference (MUI). We present a unifying all-digital Generalized
Multicarrier CDMA framework which enables us to describe existing CDMA sch
emes and to highlight thorny problems associated with them. To improve the
bit error rate (BER) performance of existing schemes, we design block FIR t
ransmitters and decision feedback (DF) receivers based on an inner-code/out
er-code principle, which guarantees MUI/ISI-elimination regardless of the f
requency-selective physical channel. The flexibility of our framework allow
s further BER enhancements by taking into account the load in the system (n
umber of active users),while blind channel estimation results in bandwidth
savings. Simulations illustrate the superiority of our framework over compe
ting MC CDMA alternatives especially in the presence of uplink multipath ch
annels.