Uplink interference protection and fair scheduling for power efficient OFDMA networks

In this paper a new method for uplink inter-cell interference coordination (ICIC) in a full frequency reuse system is proposed. The technique is named uplink interference protection (ULIP). ULIP exploits existing reference signals transmitted by all base stations (BSs). The fact that path loss and lognormal shadowing can be considered reciprocal in such frequency-division duplex (FDD) systems is exploited. Therefore, no additional signalling is required for a new mobile station (MS) to estimate the level of inter-cell interference it would cause to ongoing uplink transmissions in neighbouring cells. Using the acquired knowledge, MSs can adjust their transmit power to ensure that existing links are not forced into outage. A scheduling scheme is suggested in which a fair allocation of priority resource blocks (RBs), based on user signal-to-interference-plus-noise ratios (SINRs), enhances both cell-edge throughput and user throughput fairness. Through this, also significant system throughput gains are generated. Finally, it is demonstrated that as a side effect of the interference reductions, considerable energy savings can be achieved.