Rank recommendation-based coordinated scheduling for interference mitigation in cellular networks

An important challenge of wireless networks is to boost the cell edge performance and enable multi-streams transmissions to cell edge users. Interference mitigation techniques relying on multiple antennas and coordination among cells are nowadays heavily studied in the literature. In this paper, we propose a novel type of coordination for OFDMA networks relying on multiple antennas at the transmitter and the receiver where the transmission ranks, i.e. the number of transmitted streams, and the user scheduling in all cells are jointly optimized in order to maximize a network utility function accounting for fairness among users. A distributed coordinated scheduler relying on an interference pricing mechanism and a master-slave architecture is introduced. The proposed scheme is operated based on the user report of a recommended rank for the interfering cells. It incurs a very low feedback overhead and enables an efficient link adaptation. It is moreover robust to practical system impairments and is applicable to both open-loop and closed-loop MIMO operations. A cell edge performance gain of 20% over uncoordinated LTE-Advanced is shown through system level simulations.