Exploiting Characteristics of Slow Fading Channels in OFDMA Scheduling

The resource allocation problem has been a very hot topic since the migration from CDMA to OFDMA modulation schemes has taken place for the wireless communication systems. The scheduling problem has transformed into a rather more complex one due to the increased number of resource elements at hand. There have been numerous proposed scheduling algorithms with various analytical approaches to enhance the efficiency, QoS, fairness, or throughput of the systems that employ OFDMA. We propose an original multi-user downlink scheduling scheme for LTE where the problem is formulated as an optimization problem with minimum throughput limitations for the users. We introduce a time-window parameter to exploit the slow varying channel conditions if there are any. Specifically, this is accomplished by means of defining the minimum throughput limitation over a larger period of time than the scheduling time for users with relative slow varying channel conditions. The suggested algorithm is called the Two-Stage Time windowed Scheduling (TSTwS) and it achieves up to 30% higher average total downlink throughput than the equivalent model without the time-window approach.