Resource allocation for OFDMA/CDMA spectrum refarming system with passive infrastructure sharing

Spectrum refarming (SR) allows different generations of cellular networks to operate in the same frequency band. Infrastructure sharing involves the sharing of passive or active elements of mobile infrastructure within or among operators. Both of them are important as the cellular technology evolves. In this study, we consider an uplink OFDMA/CDMA SR system with passive infrastructure sharing, i.e., the OFDMA system and CDMA system share a common cell site while each adopting different receive antennas. Due to the cross channel state information (C-CSI) is difficult to be obtained in practice, we propose a resource allocation scheme with which the OFDMA system can provide sufficient protection to the CDMA system without C-CSI. We further propose to increase the interference margin for OFDMA resource allocation by exploiting the gap between the actual and the predicted interference suffered by CDMA users, which permits higher transmission power from OFDMA users. Simulation results have validated that the CDMA services can be protected by the proposed schemes, while the OFDMA throughput can be improved.