An Effective Multi-slot Interleaving Scheme for a Coded MC- CDMA/TDD Uplink System with Pre-equalization

摘要

In this paper, we present an effective two-step multi-slot interleaving (TS-MSI) scheme for a coded MC-CDMA/ TDD uplink system with pre-equalization, in which the polynomial-fitting and extension (PF&E) scheme is used for uplink channel estimation at a mobile transmitter. The PF&E scheme obtains uplink channel state information (CSI) estimates by extending simply the CSI polynomial approximated during some downlink slot interval to the uplink slot interval. The proposed TS-MSI scheme can obtain a higher coding gain by distributing evenly burst errors due to the inaccurateness of the uplink CSI estimates near the end of the uplink slot interval in a certain slot over all the slots in an interleaver span. Interleaving is performed in two steps as follows: (1) the interslot group-level permutation to distribute as even as possible information bits in a slot over all slots in a frame and (2) the intraslot bit-level permutation to separate as distant as possible adjacent bits in a group-level interslot-interleaved slot. Computer simulations are performed to verify the system performance under various conditions, when both the PF&E scheme and the TS-MSI scheme are used. Simulation results show that the TS-MSI scheme can gradually improve the system performance as the interleaver size increases.