3.747
Bearbeitungen
Änderungen
Zur Navigation springen
Zur Suche springen
KZeile 11:
Zeile 11: − * − * 802.11-Frame = DIFS + long_preamble + TCP + long_preamble + 802.11ack + SIFS − + − + + − + − + − + Zeile 56:
Zeile 55: − + + + + + + + + + + + + + + +
Vergleich DECT und WLAN (Quelltext anzeigen)
Version vom 20. Januar 2009, 00:43 Uhr
, 00:43, 20. Jan. 2009→WLAN-Theorie: 6mbit (noch nicht fertig)
===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
* 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
**** = 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: