Theoretical Throughput Limits

Theoretical Throughput Limits
November 2005 doc.: IEEE /1050r0 November 2005 Theoretical Throughput Limits Date: Authors: Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures < ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at Larry Green, Ixia Larry Green, Ixia

November 2005 doc.: IEEE /1050r0 November 2005 Abstract Theoretical throughput limits are calculated by a four-step methodology, assuming constant-sized data frames, based on IEEE a/b/g PHY data rates without fragmentation, RTS/CTS, management frames, collisions or retries. Upper layer protocol and application overhead is not considered. Resulting data may be used to estimate a/b/g wireless network performance. Larry Green, Ixia Larry Green, Ixia

Four Step Methodology 1. Calculate time to transmit data frame + Ack
November 2005 Four Step Methodology 1. Calculate time to transmit data frame + Ack 2. Calculate Frame Start to Frame Start Interval 3. Calculate Frame Rate 4. Calculate Theoretical Throughput Limit Methodology applied to: 802.11b CCK, Long/Short Preamble 802.11a OFDM 802.11g ERP-OFDM, DSSS-OFDM, Long/Short Preamble Larry Green, Ixia

November 2005 Terminology CWmin…minimum Contention Window time measured in Slots DIFS…Distributed Inter-frame Space (DIFS = SIFS + 2 Slots) Length…MAC data frame in bytes, including Frame Check Sequence PLCPtime…Time to transmit PLCP header PHY Rate…Data transfer rate in bits per second at PHY Layer Slot Time…Back off timing interval SIFS…Short Inter-Frame Space TxTime…Time to transmit one data frame Larry Green, Ixia

802.11b Frame Transmit Time (TxTime)
November 2005 802.11b Frame Transmit Time (TxTime) DIFS = SIFS + 2 Slots TxTime = Preamble + PLCPHeader + Ceiling(((Length + PBCC) * 8) / DataRate) Preamble SIFS: 10 usec Long: 144 Backoff slot: 20 Short: 72 CWmin: 31 PLCPHeader: 48 24 PBCC: 0 or 1 (CCK vs PBCC modulation) Note: actual frame length = data length + MAC header, etc. (additional 34 bytes) Larry Green, Ixia

802.11b TxTime (usec) November 2005 Long Preamble Short Preamble
(Bytes) 1 2 5.5 11 (Ack) 14 304 248 213 203 152 117 107 20 624 408 271 232 312 175 136 40 784 488 300 246 392 204 150 64 976 584 335 264 239 168 128 1488 840 428 310 744 332 214 256 2512 1352 614 403 1256 518 307 512 4560 2376 987 590 2280 891 494 1024 8656 4424 1731 962 4328 1635 866 1280 10704 5448 2104 1148 5352 2008 1052 1500 12464 6328 2424 1308 6232 2328 1212 1518 12608 6400 2450 1321 6304 2354 1225 2312 18960 9576 3605 1899 9480 3509 1803 Larry Green, Ixia

November 2005 802.11b Frame Start to Frame Start Interval FS to FS Interval = TxTime + SIFS + AckTime + DIFS + Random Backoff Ack Frame = 14 1 Mbps DIFS = SIFS + 2 Backoff Slots Average Backoff Slots = CWmin/2 Long Preamble Short Preamble (Bytes) 1 2 5.5 11 20 1288 1016 844 795 824 652 603 40 1448 1096 873 809 904 681 617 64 1640 1192 908 827 1000 716 635 128 2152 1001 1256 256 3176 1960 1187 966 1768 995 774 512 5224 2984 1560 1153 2792 1368 961 1024 9320 5032 2304 1525 4840 2112 1333 1280 11368 6056 2677 1711 5864 2485 1519 1500 13128 6936 2997 1871 6744 2805 1679 1518 13272 7008 3023 1884 6816 2831 1692 2312 19624 10184 4178 2462 9992 3986 2270 Larry Green, Ixia

802.11b Frame Rate (Frames per Second)
November 2005 802.11b Frame Rate (Frames per Second) Long Preamble Short Preamble (Bytes) 1 2 5.5 11 20 776 984 1184 1257 1213 1533 1658 40 690 912 1145 1236 1106 1468 1620 64 609 838 1101 1209 1000 1396 1574 128 464 999 796 256 314 510 842 1035 565 1005 1291 512 191 335 641 867 358 730 1040 1024 107 198 434 655 206 473 750 1280 87 165 373 584 170 402 658 1500 76 144 333 534 148 356 595 1518 75 142 330 530 146 353 591 2312 50 98 239 406 100 250 440 Larry Green, Ixia

802.11b Theoretical Throughput Limits (Mbps)
November 2005 802.11b Theoretical Throughput Limits (Mbps) Long Preamble Short Preamble (Bytes) 1 2 5.5 11 20 0.12 0.16 0.19 0.20 0.25 0.27 40 0.22 0.29 0.37 0.40 0.35 0.47 0.52 64 0.31 0.43 0.56 0.62 0.51 0.71 0.81 128 0.48 1.02 1.17 0.82 1.27 1.50 256 0.64 1.04 1.72 2.12 1.16 2.06 2.64 512 0.78 1.37 2.63 3.55 1.47 2.99 4.26 1024 0.88 1.62 3.56 5.37 1.69 3.87 6.14 1280 0.89 3.82 5.98 1.74 4.12 6.74 1500 0.91 1.73 4.00 6.41 1.78 4.27 7.14 1518 4.01 6.44 1.77 4.29 7.18 2312 0.92 1.81 4.42 7.51 1.85 4.62 8.14 Larry Green, Ixia

802.11a Frame Transmit Time (TxTime)
November 2005 802.11a Frame Transmit Time (TxTime) DIFS = SIFS + 2 Slots TxTime = Tpreamble + Tsignal + Tsym * Ceiling((16 + (8 * Length) + 6) / Ndbps) Tpreamble: 16 usec SIFS: Tsignal: 4 Backoff slot: 9 Tsym: CWmin: 15 Ndbps = number of data bits per symbol (function of transmit rate): Transmit Rate (Mbps) 6 12 18 24 36 48 54 Ndbps: 72 96 144 192 216 Note: actual frame length = data length + MAC header, etc. (additional 34 bytes) Larry Green, Ixia

802.11a Frame Transmit Time (TxTime) (usec)
November 2005 802.11a Frame Transmit Time (TxTime) (usec) (Bytes) 6 9 12 18 24 36 48 54 (Ack) 14 44 32 28 20 96 72 60 40 124 92 56 64 156 112 88 68 128 240 168 132 76 256 412 284 216 152 120 512 752 508 388 264 204 144 104 1024 1436 964 728 492 376 200 180 1280 1776 1192 900 608 460 316 1500 2072 1388 1048 704 536 364 280 248 1518 2096 1404 1060 712 540 368 252 2312 3152 2108 1588 1064 804 544 Larry Green, Ixia

November 2005 802.11a Frame Start to Frame Start Interval FS to FS Interval = TxTime + SIFS + AckTime + DIFS + Random Backoff Ack Frame = 14 6 Mbps DIFS = SIFS + 2 Backoff Slots Average Backoff Slots = CWmin/2 (Bytes) 6 9 12 18 24 36 48 54 20 253 221 205 189 181 173 169 40 281 241 217 197 177 64 313 261 233 209 128 397 317 277 237 185 256 569 433 361 293 225 201 512 909 657 533 405 345 249 1024 1593 1113 873 633 517 393 337 1280 1933 1341 1045 749 601 453 377 353 1500 2229 1537 1193 845 677 501 417 385 1518 2253 1553 1205 853 681 505 389 2312 3309 2257 1733 945 549 Larry Green, Ixia

802.11a Frame Rate (Frames per Second)
November 2005 802.11a Frame Rate (Frames per Second) (Bytes) 6 9 12 18 24 36 48 54 20 3952 4524 4878 5291 5524 5780 5917 40 3558 4149 4608 5076 5649 64 3194 3831 4291 4784 128 2518 3154 3610 4219 5405 256 1757 2309 2770 3412 4444 4975 512 1100 1522 1876 2469 2898 4016 1024 627 898 1145 1579 1934 2544 2967 1280 517 745 956 1335 1663 2207 2652 2832 1500 448 650 838 1183 1477 1996 2398 2597 1518 443 643 829 1172 1468 1980 2570 2312 302 577 1058 1821 Larry Green, Ixia

802.11a Theoretical Throughput Limits (Mbps)
November 2005 802.11a Theoretical Throughput Limits (Mbps) (Bytes) 6 9 12 18 24 36 48 54 20 0.63 0.72 0.78 0.85 0.88 0.92 0.95 40 1.14 1.33 1.47 1.62 1.69 1.81 1.85 1.89 64 1.64 1.96 2.20 2.45 2.60 2.83 2.89 2.96 128 2.58 3.23 3.70 4.32 4.72 5.20 5.53 256 3.60 4.73 5.67 6.99 7.85 9.10 9.80 10.19 512 4.51 6.23 7.68 10.11 11.87 14.57 16.45 16.99 1024 5.14 7.36 9.38 12.94 15.84 20.84 24.31 25.84 1280 5.29 7.63 9.79 13.67 17.03 22.60 27.16 29.00 1500 5.38 7.80 10.06 14.20 17.72 23.95 28.78 31.16 1518 7.81 10.07 14.23 17.83 24.05 29.12 31.21 2312 5.59 8.19 10.67 15.33 19.57 27.15 33.68 36.62 Larry Green, Ixia

802.11g Frame Transmit Time (TxTime) ERP OFDM
November 2005 802.11g Frame Transmit Time (TxTime) ERP OFDM TxT = Tpreamble + Tsignal + Tsym * Ceiling((16 + (8 * Length) + 6) / Ndbps) + SigExt Tpreamble: 16 usec SIFS: 10 Tsignal: 4 Backoff slot: 9 Tsym: CWmin: 15 SigExt: 6 Ndbps = number of data bits per symbol (function of PHY Rate): Transmit Rate (Mbps) 12 18 24 36 48 54 Ndbps: 72 96 144 192 216 Larry Green, Ixia

802.11g Frame Transmit Time (TxTime)
November 2005 802.11g Frame Transmit Time (TxTime) ERP OFDM (Bytes) 6 9 12 18 24 36 48 54 (Ack) 14 50 42 38 34 30 20 102 78 66 46 40 130 98 62 64 162 118 94 74 128 246 174 138 82 256 418 290 222 158 126 70 512 758 514 394 270 210 150 110 1024 1442 970 734 498 382 262 206 186 1280 1782 1198 906 614 466 322 1500 2078 1394 1054 710 542 370 286 254 1518 2102 1410 1066 718 546 374 258 2312 3158 2114 1594 1070 810 550 Larry Green, Ixia

November 2005 802.11g Frame Start to Frame Start Interval FSI = TxT + SIFS + AckTime + DIFS + Random Backoff Ack Frame = 14 1 Mbps DIFS = SIFS + 2 Backoff Slots Average Backoff Slots = CWmin/2 ERP OFDM (Bytes) 6 9 12 18 24 36 48 54 20 253 221 205 189 181 173 169 40 281 241 217 197 177 64 313 261 233 209 128 397 317 277 237 185 256 569 433 361 293 225 201 512 909 657 533 405 345 249 1024 1593 1113 873 633 517 393 337 1280 1933 1341 1045 749 601 453 377 353 1500 2229 1537 1193 845 677 501 417 385 1518 2253 1553 1205 853 681 505 389 2312 3309 2257 1733 945 549 Larry Green, Ixia

802.11g Frame Rate (ERP OFDM Frames per Second)
November 2005 802.11g Frame Rate (ERP OFDM Frames per Second) ERP-OFDM (Bytes) 6 9 12 18 24 36 48 54 20 3952 4524 4878 5291 5524 5780 5917 40 3558 4149 4608 5076 5649 64 3194 3831 4291 4784 128 2518 3154 3610 4219 5405 256 1757 2309 2770 3412 4444 4975 512 1100 1522 1876 2469 2898 4016 1024 627 898 1145 1579 1934 2544 2967 1280 517 745 956 1335 1663 2207 2652 2832 1500 448 650 838 1183 1477 1996 2398 2597 1518 443 643 829 1172 1468 1980 2570 2312 302 577 1058 1821 Larry Green, Ixia

802.11g ERP OFDM Theoretical Throughput Limits (Mbps)
November 2005 802.11g ERP OFDM Theoretical Throughput Limits (Mbps) ERP OFDM (Bytes) 6 9 12 18 24 36 48 54 20 0.63 0.72 0.78 0.85 0.88 0.92 0.95 40 1.14 1.33 1.47 1.62 1.69 1.81 1.85 1.89 64 1.64 1.96 2.20 2.45 2.60 2.83 2.89 2.96 128 2.58 3.23 3.70 4.32 4.72 5.20 5.53 256 3.60 4.73 5.67 6.99 7.85 9.10 9.80 10.19 512 4.51 6.23 7.68 10.11 11.87 14.57 16.45 16.99 1024 5.14 7.36 9.38 12.94 15.84 20.84 24.31 25.84 1280 5.29 7.63 9.79 13.67 17.03 22.60 27.16 29.00 1500 5.38 7.80 10.06 14.20 17.72 23.95 28.78 31.16 1518 7.81 10.07 14.23 17.83 24.05 29.12 31.21 2312 5.59 8.19 10.67 15.33 19.57 27.15 33.68 36.62 Larry Green, Ixia

802.11g DSSS OFDM Transmit Time (TxTime) (usec)
November 2005 802.11g DSSS OFDM Transmit Time (TxTime) (usec) TxT = TdsssPreamble + TdsssHeader + TofdmPreamble + Tsignal + 4 * ceiling((16 + (8 * Length) + 6) / Ndbps) + SigExt PreambleLength: TofdmPreamble: 8 usec Long: 144 Tsignal: 4 Short: 72 SigExt: 6 PLCPHeaderTime: 48 SIFS: 10 24 Backoff Slot: 20 CWmin: 31 Larry Green, Ixia

802.11g DSSS OFDM Transmit Time (TxTime) (usec)
November 2005 802.11g DSSS OFDM Transmit Time (TxTime) (usec) DSSS OFDM Short Preamble (Bytes) 6 9 12 18 24 36 48 54 (Ack) 14 138 130 126 122 118 20 190 166 154 142 134 40 218 186 150 64 250 206 182 162 128 334 262 226 170 256 506 378 310 246 214 158 512 846 602 482 358 298 238 198 1024 1530 1058 822 586 470 350 294 274 1280 1870 1286 994 702 554 410 1500 2166 1482 1142 798 630 458 374 342 1518 2190 1498 1154 806 634 462 346 2312 3246 2202 1682 1158 898 638 Larry Green, Ixia

DSSS OFDM Short Preamble
November 2005 802.11g Frame Start to Frame Start Interval FS to FS Interval = TxTime + SIFS + tAck + DIFS + Random Backoff Ack Frame = 14 1 Mbps DIFS = SIFS + 2 Backoff Slots Average Backoff Slots = CWmin/2 DSSS OFDM Short Preamble (Bytes) 6 9 12 18 24 36 48 54 20 688 656 640 624 616 608 604 40 716 676 652 632 612 64 748 696 668 644 128 832 752 712 672 620 256 1004 868 796 728 660 636 512 1344 1092 968 840 780 684 1024 2028 1548 1308 1068 952 828 772 1280 2368 1776 1480 1184 1036 888 812 788 1500 2664 1972 1628 1112 936 852 820 1518 2688 1988 1640 1288 1116 940 824 2312 3744 2692 2168 1380 984 Larry Green, Ixia

802.11g Frame Rate (Frames per Second)
November 2005 802.11g Frame Rate (Frames per Second) DSSS OFDM Short Preamble (Bytes) 6 9 12 18 24 36 48 54 20 1453 1524 1562 1602 1623 1644 1655 40 1396 1479 1533 1582 1633 64 1336 1436 1497 1552 128 1201 1329 1404 1488 1612 256 996 1152 1256 1373 1515 1572 512 744 915 1033 1190 1282 1461 1024 493 645 764 936 1050 1207 1295 1280 422 563 675 844 965 1126 1231 1269 1500 375 507 614 781 899 1068 1173 1219 1518 372 503 609 776 896 1063 1213 2312 267 371 461 724 1016 Larry Green, Ixia

802.11g Theoretical Throughput Limits (Mbps)
November 2005 802.11g Theoretical Throughput Limits (Mbps) DSSS OFDM Short Preamble (Bytes) 6 9 12 18 24 36 48 54 20 0.23 0.24 0.25 0.26 40 0.45 0.47 0.49 0.51 0.52 0.53 64 0.68 0.74 0.77 0.79 0.81 0.83 0.84 128 1.23 1.36 1.44 1.52 1.57 1.62 1.65 256 2.04 2.36 2.57 2.81 2.94 3.10 3.18 3.22 512 3.05 3.75 4.23 4.87 5.25 5.72 5.98 6.06 1024 4.04 5.28 6.26 7.67 8.60 9.89 10.61 10.89 1280 4.32 5.77 6.91 8.64 9.88 11.53 12.61 12.99 1500 4.50 6.08 7.37 9.37 10.79 12.82 14.08 14.63 1518 4.52 6.11 7.40 9.42 10.88 12.91 14.24 14.73 2312 4.94 6.86 8.53 11.26 13.39 16.57 18.79 19.66 Larry Green, Ixia

802.11g Frame Transmit Time (TxTime) (usec)
November 2005 802.11g Frame Transmit Time (TxTime) (usec) DSSS OFDM Long Preamble (Bytes) 6 9 12 18 24 36 48 54 (Ack) 14 234 226 222 218 214 20 286 262 250 238 230 40 314 282 246 64 346 302 278 258 128 430 358 322 266 256 602 474 406 342 310 254 512 942 698 578 454 394 334 294 1024 1626 1154 918 682 566 446 390 370 1280 1966 1382 1090 798 650 506 1500 2262 1578 1238 894 726 554 470 438 1518 2286 1594 1250 902 730 558 442 2312 3342 2298 1778 1254 994 734 Larry Green, Ixia

DSSS OFDM Long Preamble
November 2005 802.11g Frame Start to Frame Start Interval FS to FS Interval = TxTime + SIFS + AckTime + DIFS + Random Backoff Ack Frame = 14 1 Mbps DIFS = SIFS + 2 Backoff Slots Average Backoff Slots = CWmin/2 DSSS OFDM Long Preamble (Bytes) 6 9 12 18 24 36 48 54 20 880 848 832 816 808 800 796 40 908 868 844 824 804 64 940 888 860 836 128 1024 944 904 864 812 256 1196 1060 988 920 852 828 512 1536 1284 1160 1032 972 876 2220 1740 1500 1260 1144 1020 964 1280 2560 1968 1672 1376 1228 1080 1004 980 2856 2164 1820 1472 1304 1128 1044 1012 1518 2880 2180 1832 1480 1308 1132 1016 2312 3936 2884 2360 1572 1176 Larry Green, Ixia

802.11g Frame Rate (Frames per Second)
November 2005 802.11g Frame Rate (Frames per Second) DSSS OFDM Long Preamble (Bytes) 6 9 12 18 24 36 48 54 20 1136 1179 1201 1225 1237 1250 1256 40 1101 1152 1184 1213 1243 64 1063 1126 1162 1196 128 976 1059 1106 1157 1231 256 836 943 1012 1086 1173 1207 512 651 778 862 968 1028 1141 1024 450 574 666 793 874 980 1037 1280 390 508 598 726 814 925 996 1020 1500 350 462 549 679 766 886 957 988 1518 347 458 545 675 764 883 984 2312 254 346 423 636 850 Larry Green, Ixia

802.11g Theoretical Throughput Limits (Mbps)
November 2005 802.11g Theoretical Throughput Limits (Mbps) DSSS OFDM Long Preamble (Bytes) 6 9 12 18 24 36 48 54 20 0.18 0.19 0.20 40 0.35 0.37 0.38 0.39 0.40 64 0.54 0.58 0.59 0.61 0.62 0.63 0.64 128 1.00 1.08 1.13 1.18 1.21 1.24 1.26 256 1.71 1.93 2.07 2.22 2.31 2.40 2.45 2.47 512 2.67 3.19 3.53 3.96 4.21 4.51 4.67 4.72 1024 3.69 4.70 5.46 6.50 7.16 8.03 8.50 8.68 1280 3.99 5.20 6.12 7.43 8.34 9.47 10.20 10.44 1500 4.20 5.54 6.59 8.15 9.19 10.63 11.48 11.86 1518 5.56 6.62 8.20 9.28 10.72 11.62 11.95 2312 6.40 7.82 10.08 11.76 14.13 15.72 16.33 Larry Green, Ixia

References IEEE 802.11-2005 IEEE 802.11 Handbook
November 2005 References IEEE IEEE Handbook O’Hara, Petrick, Godfrey, Second Edition, IEEE Press Benchmarking Methodology for Wireless LAN Devices Alexander, Bradner, IETF Working Group, April, 2005 Throughput and Delay Limits of IEEE Xiao, Rosdahl, IEEE Communication Letters, August, 2002 Larry Green, Ixia

Theoretical Throughput Limits

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