System Level Modeling and Optimization of the LTE Downlink

5. Performance Evaluation of Fractional Frequency Reuse in LTEresults shown in Figures 5.8 and 5.9, the following conclusions are drawn:ˆ Without losing any mean throughput or fairness with respect to the reuse-1 case,it is possible to obtain obtain an additional 15% average throughput, 50% edgethroughput, and 10% peak throughput.ˆ Constrained to not losing any mean throughput, fairness can be improved to 0.85,which doubles edge throughput at the cost of a 20 % loss of peak throughput.ˆ It is possible to maximally increase fairness up to 0.93 by sacrificing 15% mean,and 45% peak throughput, as well as a being able to set fairness to a variety ofpoints in-between.fairness0.950.90.850.8optimum trade-off betweenfairness and mean throughputno mean throughput loss,increased fairness0.750.7−30 −25 −20−15 −10 −5 0 5 10 15Mean throughput gain (%)2.4 2.6 2.8 3 3.2 3.4 3.6 3.8Mean throughput (Mbit/s)no fairness loss,increased mean throughputFigure 5.9: Trade-off between fairness and mean throughput for round robin scheduling.Red: optimum fairness-to-mean-throughput trade-off envelope.Edge throughput (Mbit/s)1.81.61.41.210.80.60.40.2Edge throughput gain (%)150100500−50Edge-Mean throughput trade-off−30 −25−20−15−10 −5 0 5 10 15Mean throughput gain (%)2.4 2.6 2.8 3 3.2 3.4 3.6 3.8Mean throughput (Mbit/s)Peak throughput (Mbit/s)87.576.565.554.543.5Peak throughput gain (%)100−10−20−30−40−50Peak-Mean throughput trade-off−30−25−20−15−10 −5 0 5 10 15Mean throughput gain (%)2.4 2.6 2.8 3 3.2 3.4 3.6 3.8Mean throughput (Mbit/s)Figure 5.10: Left: Trade-off between edge throughput and mean throughput (round robinscheduling). Left: Trade-off between peak throughput and mean throughput.Marked red: optimum fairness-to-mean-throughput trade-off.75