STUDY AND PERFORMANCE OF FAIR SCHEDULING ALGORITHMS IN OFDMA

Abstract

In this dissertation work, different types of fair resource scheduling algorithms for OFDMA system have been discussed and their performances are compared with the algorithms for which fairness is no criterion. Time varying nature of the wireless channel creates a problem in efficient allocation of the subcarriers to the users. Hence, adaptive modulation technique is used in allocation of bits to the subcarriers. In this dissertation, the performance of minimum normalized transmit rate based fair scheduling algorithm has been evaluated which uses the adaptive modulation technique. Using the instantaneous channel gains of each subcarrier corresponding to each user, maximum number of bits that each user can allocate to each subcarrier, is calculated. Then utilization efficiency of each subcarrier corresponding to each user is calculated. Utilization efficiency of a subaccier-user pair is the ratio of the bits that the user can allocate to the subcarrier, to the total number of bits that each user can allocate to the subcarrier. To provide fairness among users, the user with the minimum normalized transmit rate is selected and to achieve high throughput the subcarrier corresponding to this user with the highest utilization efficiency is selected. Simulation results show that a high throughput is achieved while providing fairness.