Re: limits of 802.11b sensitivity
Jim Thompson <[email protected]>
| Newsgroups | gmane.network.wireless.bay-area |
|---|---|
| Message-ID | <[email protected]> |
On Aug 5, 2004, at 12:36 PM, Daniel Dobkin wrote: > Folks: > > I'm not quite sure who was doing the calculation but... > > << Theoretical receive sensitivity can be calculated as: >> >> Receive sensitivity = Nt + Ns + SNRmin >> >> where Nt is the thermal noise floor, Ns is the system noise figure, >> and SNRmin is the minimum SNR required for a given bit-error rate. >> >> 802.11b's CCK requires a SNR of about 10dB to decode frames with a FER >> of 0.08. (We'll leave SIR and/or SINR out of the discussion unless >> someone insists.) We'll call this SNRmin. > >> > > The required channel (S/N) for CCK11 to achieve a packet error rate of > 0.08 is about 7 dB, not 10 dB [source: fig 2.16 of "Evolution of 2.4 > GHz Wireless LANs", Heegard et. al., in "Wireless Local Area > Networks", ed. Bing, Wiley 2003]. Perhaps in theory. I urge you to check the documentation on the baseband in use on this card. It is (ahem) much closer to the figure I used. > The noise effective bandwidth of the 802.11 signal is also closer to > 16 MHz rather than the 22 MHz needed to incorporate all the power. > The thermal noise floor is thus about -101 dBm. I'm willing to deal with -101dBm as a thermal noise floor. Jim _______________________________________________ BAWUG's general wireless chat mailing list [unsubscribe] http://lists.bawug.org/mailman/listinfo/wireless