On Thu, Jan 14, 2010 at 3:27 PM, Jaswinder Singh Rajput <jaswindermobile@xxxxxxxxx> wrote: > I run these tests on Wireless A/G. > > Can you please let me know what are the overheads for this performance > degradation. 802.11 MAC, plus IP headers, etc. E.g. in the MAC, a single packet transmission includes the DCF interfame space, physical layer headers, an exponential backoff term, plus the time for an ACK from the recipient. You can get more exact info from the 802.11 spec, but it is something like (from memory) 34 us for DIFS, another 20 us or so for PLCP, between 0 and 135 us for backoff term, then 4 us per OFDM symbol, which for 1500 byte packet at 54 mbps works out to ~224 us. So, that's ~413 us to send 1500*8 bits, or an actual rate of 29 Mbps not counting the ACK. It goes down from there with retransmissions and the rest. -- Bob Copeland %% www.bobcopeland.com -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
