Reduced interference MC-CDMA system using Discrete Prolate codes

Multiple Access Interference (MAI) imposes serious limitation to the MC-CDMA systems´ performance in uplink channel. In our proposal we are considering a system where orthogonal users´ codes are based on Prolate Spheroidal Functions (PSF), specifically those denominated Periodic Discrete Prolate Spheroidal Sequences (PDPSS). These codes have the property concentrating signal energy in the desired time interval and gives the possibility to avoid Inter Symbol Interference (ISI) for a certain number of users without introducing the guard interval between consecutive symbols. Furthermore, it is also possible to avoid completely MAI for a certain number of active users in the uplink channel. Even in the case when this limit is passed, MAI is below the standard MC-CDMA schemes. Preliminary simulations presented here demonstrate this affirmation.