Opportunistic Uplink Retransmission Control with Active-User Estimation in Multi-User Packet CDMA Systems

This paper presents an uplink retransmission control scheme to improve the system throughput based on the active-user estimation capabilities offered by Kalman filtering in a multiuser single CDMA cell. The improvement is achieved by means of selecting the best subset of users with the power- controlled opportunistic retransmission control (PORC) based on the radio resources reservation and a joint PHY-MAC opportunity function, which also takes the channel information and the waiting time into account. Simulation results show that the proposed strategy exhibits significant improvement in terms of throughput and fairness.