Modification of Round Robin and Best CQI Scheduling Method for 3GPP LTE Downlink

Abstract

In the downlink LTE, the scheduler is an important element that assigns resource block (RB) allocation for different users in a cell. RB is the smallest element that can be assigned by the scheduler. This paper proposed a new scheduler algorithm by considering the tradeoff balance between throughput and fairness among users. The benefits of both Best CQI and Round Robin schedulers have been combined in this proposed scheduler. The proposed scheduler has two main time slots that apply the combined algorithms. The primary time slot applies a Round Robin algorithm that has a continuous user sequence in the entire sub frame, and the second time slot then applies the Best CQI algorithm with a fairness enhancement. For 15dB SNR, the system has various throughput values in each scheduler, which is 61.2Mbps for the Best CQI scheduler, 32.3Mbps for the Round Robin scheduler, and 48Mbps for the proposed scheduler. For the results, in reference to Jain's fairness index, the proposed scheduler gains a fairness index of 0.97. Furthermore, for 20 users at 5MHz bandwidth, it is found that the average queuing delay is 5ms for the Round Robin scheduler, 29.38ms for the Best CQI scheduler, and 0.94ms for the proposed scheduler.