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Zeile 11: |
| ===WLAN-Theorie=== | | ===WLAN-Theorie=== |
| * theoretisches Maximum bei 1460 Bytes Nutzlast, TCP-Stream | | * theoretisches Maximum bei 1460 Bytes Nutzlast, TCP-Stream |
− | *
| |
| * SIFS = '''S'''hort '''I'''nter'''f'''rame '''S'''pace | | * SIFS = '''S'''hort '''I'''nter'''f'''rame '''S'''pace |
| * DIFS = '''D'''istributed '''I'''nter'''f'''rame '''S'''pace (-> kann variieren wegen "collision avoidance" + "exponential backoff") | | * DIFS = '''D'''istributed '''I'''nter'''f'''rame '''S'''pace (-> kann variieren wegen "collision avoidance" + "exponential backoff") |
| * SNAP = '''S'''ubnetwork '''A'''ccess '''P'''rotocol | | * SNAP = '''S'''ubnetwork '''A'''ccess '''P'''rotocol |
− | * 802.11-Frame = DIFS + long_preamble + TCP + long_preamble + 802.11ack + SIFS
| |
| * TCP_HEADER/DATA bei MTU 1500 = 1460 Bytes + 40 Bytes Header + 28 Bytes Control/Management + 8 SNAP = 1536 Bytes | | * TCP_HEADER/DATA bei MTU 1500 = 1460 Bytes + 40 Bytes Header + 28 Bytes Control/Management + 8 SNAP = 1536 Bytes |
| * TCP_HEADER/ACK = 40 Bytes Header + 28 Bytes Control/Management + 8 SNAP = 76 Bytes | | * TCP_HEADER/ACK = 40 Bytes Header + 28 Bytes Control/Management + 8 SNAP = 76 Bytes |
| | | |
− | ** '''1 mbit''': | + | ** '''1 mbit''' |
− | *** preamble long/short: 192 / 96 µs | + | *** Modulation: Differential Binary Phase Shift Keying (DBPSK/D2PSK) |
| + | *** preamble("slot") long/short: 192 / 96 µs |
| *** 802.11ack = 14 Bytes | | *** 802.11ack = 14 Bytes |
− | *** 8 Bit / Symbol -> 1375000 Symbole / 11 / Sekunde = 125000 Symbole/s | + | *** 1 Nutzdatenbit / Symbol -> 0,125 mSymbole/s (1.375.000 Symbole je 8 Bit @ 11mbit) |
| *** SIFS / SLOT / DIFS = 10 µs / 20 µs / 2 x SLOT + SIFS = 50 µs | | *** SIFS / SLOT / DIFS = 10 µs / 20 µs / 2 x SLOT + SIFS = 50 µs |
| *** 802.11-Frame = DIFS + long_preamble + TCP + long_preamble + 802.11ack + SIFS | | *** 802.11-Frame = DIFS + long_preamble + TCP + long_preamble + 802.11ack + SIFS |
| *** TCP-DATA: | | *** TCP-DATA: |
| **** = DIFS + long_preamble + TCP_HEADER/DATA + long_preamble + 802.11ack + SIFS | | **** = DIFS + long_preamble + TCP_HEADER/DATA + long_preamble + 802.11ack + SIFS |
− | **** = 50 + 192 + (1536 Bytes/1,375 mSymbole*11)=12288 + 192 + (14/1,375*11)=112 + 10 = 12844 µs | + | **** = 50 + 192 + (1536 Bytes/0.125 mSymbole)=12288 + 192 + (14/1,375*11)=112 + 10 = 12844 µs |
| *** TCP-ACK: | | *** TCP-ACK: |
| **** = DIFS + long_preamble + TCP_HEADER/ACK + long_preamble + 802.11ack + SIFS | | **** = DIFS + long_preamble + TCP_HEADER/ACK + long_preamble + 802.11ack + SIFS |
− | **** = 50 + 192 + (76 Bytes/1,375 mSymbole*11)=608 + 192 + (14/1,375*11)=112 + 10 = 1164 µs | + | **** = 50 + 192 + (76 Bytes/0.125 mSymbole)=608 + 192 + (14/1,375*11)=112 + 10 = 1164 µs |
| *** ALL: | | *** ALL: |
| **** = 12844 + 1164 = 14008 µs => 71,3 Frames/s * 1460 Bytes Nutzlast = '''104.226 Bytes/s''' = 6253 kB/min | | **** = 12844 + 1164 = 14008 µs => 71,3 Frames/s * 1460 Bytes Nutzlast = '''104.226 Bytes/s''' = 6253 kB/min |
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Zeile 55: |
| **** = 2412 + 972 = 3384 µs => 295,5 Frames/s * (1460/6)=243,3 Bytes Nutzlast = '''71.895 Bytes/s''' = 4313 kB/min | | **** = 2412 + 972 = 3384 µs => 295,5 Frames/s * (1460/6)=243,3 Bytes Nutzlast = '''71.895 Bytes/s''' = 4313 kB/min |
| | | |
− | ** 6mbit: | + | ** '''6mbit , 802.11g-only, no protection''' |
| + | *** Modulation: BPSK/ERP-OFDM |
| + | *** preamble("slot") long/short: 20 / 9 µs |
| + | *** 802.11ack = 14 Bytes |
| + | *** 250.000 Symbole je 24 Nutzbits @ 6 mbit/s (4 µs/Symbol) |
| + | *** SIFS / SLOT / DIFS = 10 µs / 9 µs (short_slot) / 2 x SLOT + SIFS = 28 µs |
| + | *** SIFS / SLOT / DIFS = 10 µs / 20 µs ( long_slot) / 2 x SLOT + SIFS = 50 µs |
| + | *** TCP-DATA: |
| + | *** 802.11-Frame = DIFS + long_preamble + TCP + long_preamble + 802.11ack + SIFS |
| + | **** = 28 + 20 + (1536Byte/3Byte_pro_Symbol=512 Symbole je 4 µs + 6 µs Signal Extension)=2054 + 10 + 20 + (14Byte/3Byte_pro_Symbol=5 Symbole je 4 µs + 6 µs Signal Extension)=26 + 10 = 2168 µs |
| + | *** TCP-ACK: |
| + | **** = 28 + 20 + (76Byte/3Byte_pro_Symbol=26 Symbole je 4 µs + 6 µs Signal Extension)=110 + 10 + 20 + (14Byte/3Byte_pro_Symbol=5 Symbole je 4 µs + 6 µs Signal Extension)=26 + 10 = 224 µs |
| + | *** ALL: |
| + | **** = 2168 + 224 = 2392 µs => 418 Frames/s * 1460 Bytes Nutzlast = '''610.367 Bytes/s''' = 36.622 kB/min |
| + | |
| ** 12mbit: | | ** 12mbit: |
| ** 18mbit: | | ** 18mbit: |