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Chapter 4Simulation and analytical modelling pMean Access Delay (ms)Mean Access Delay (ms)807060504030201001009080706050403020100(a) Meand Access Delay for 64-byte packetsTheoreticalSeed-44Seed-131Seed-224Seed-257Seed-300Seed-452Seed-569Seed-664Seed-742Seed-809Seed-9480 25 50 75 100 125 150 175 200 225 250Offered Load (kbps)(c) Meand Access Delay for 128-byte packetsTheoreticalSeed-44Seed-131Seed-224Seed-257Seed-300Seed-452Seed-569Seed-664Seed-742Seed-809Seed-9480 50 100 150 200 250 300 350 400 450 500Offered Load (kbps)Throughput (kbps)Throughput (kbps)2502252001751501251007550250500450400350300250200150100500(b) Throughput for 64-byte packetsTheoreticalSeed-44Seed-131Seed-224Seed-257Seed-300Seed-452Seed-569Seed-664Seed-742Seed-809Seed-9480 25 50 75 100 125 150 175 200 225 250Offered Load (kbps)(d) Throughput for 128-byte packetsTheoreticalSeed-44Seed-131Seed-224Seed-257Seed-300Seed-452Seed-569Seed-664Seed-742Seed-809Seed-9480 50 100 150 200 250 300 350 400 450 500Offered Load (kbps)Figure 4.20 – Mean access delay and throughput for different seeds.to be under 3% with an offered load up to ≈ 98% of the maximum channel capacity.This deviation was found to be under ≈ 2% for system throughput (Figure 4.18).Simulation results presented in the previous two figures were obtained with a seed of257.We also used different seeds for simulation results in order to verify the accuracy ofthe simulation model. Figure 4.20 shows the performance analysis when ten randomseeds were used (selected in the range from 0 to 1000) for 6 4 and 128 byes packetsizes. Results for mean access delays revealed that all seeds follow the same distributionas that of the theoretical results. For offered loads under 95% of the maximumtheoretical throughput, the maximum deviation was still under 3%. For offered loadsclose to saturation (from 96 to 99%) the deviation was seen to be about 4%. However,the maximum deviation in terms of throughput was unchanged at 2%.4-34