Adaptive MMSE/pcPIC-MMSE multiuser detector for MC-CDMA satellite system

Future broadband satellite systems, supporting user terminal mobility, will employ regenerative LEO satellites with multiple spot-beams per satellite. MC-CDMA is a promising multiple-access technique for these systems, because it exploits the advantages of both OFDM and CDMA. However, the detector design for the reverse link, taking into account both intra- and inter-beam interference, is still an open area of research. In this paper, we propose a new MC-CDMA multiuser detector, that can deal with both intra- and inter-beam interference in frequency-selective fading channels. The ideal detector consists of an initial linear MMSE stage and possibly multiple nonlinear pcPIC-MMSE stages, that act on a per-carrier basis. Furthermore, to take care of its initialisation, we devised a training-based fully adaptive detector, that does not require any a priori information and achieves the same steady-state performance as the ideal detector. The MMSE/pcPIC-MMSE detector outperforms a classical MMSE detector by 4 dB for a BER of 10 ^-2, while still maintaining linear complexity in the number of users