At the end of the day, its all S(I)NR and coding gain. Lowering the bitrate reduces the required S(I)NR and/or coding gain (due to modulation), as does running in clean(er) spectrum (less 'I').
Soon someone will say "breakpoint model", and I'll start screaming. Jim Patrick Leary writes: > Tim, your understanding of OFDM is way off. Extraordinarily stability is > achieved with OFDM - far more than with our FHSS or our DSSS. We have > examples of links having only a single packet error over several weeks. I am > not basing these off theory, but off actual field results both beta and > commercial deployments. Here is a link to some such tests done using our > 3.5GHz OFDM PMP which has been shipping for 18 months and is in use in major > carrier deployments around the world. This paper includes detailed photo > examples of the links. > > http://www.alvarion-usa.com/RunTime/Materials/KnowledgePoolFiles/alv_OFDM%20 > wp.pdf > > Keep in mind, this is 3.5GHz equipment > http://www.alvarion-usa.com/RunTime/Products_2020.asp?tNodeParam=33working > off a very small channelization, so the max data rate is lower than our same > products using 20MHz 5GHz channels (BreezeACCESS VL and BreezeACCESS LB). > VL: http://www.alvarion-usa.com/RunTime/Products_2020.asp?tNodeParam=39 > LB: http://www.alvarion-usa.com/RunTime/Products_2020.asp?tNodeParam=35 > > Patrick > Alvarion > > > > -----Original Message----- > From: 'Tim Pozar' [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 24, 2003 8:43 PM > To: Patrick Leary > Cc: Ladjicke Diouf; [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: Re: [BAWUG] 802.11b Long Range non line of sight > > > On Thu, Jul 24, 2003 at 05:32:38PM -0700, Patrick Leary wrote: > > Tim, I am not sure if you are talking about OFDM or DSSS. With OFDM, you > > DON'T need LOS. Of course its not going to connect forever with NLOS, but > > for a few miles, it is a no brainer. We have ample empirical data that > > proves it. > > I haven't see your report but if you are basing it on using things > like knife-edge diffraction or even multipath as your method of > getting from point A to point B. I *would* be cautious about giving > the link a high "up-time". > > Looking forward to the report... > > Tim > > > This mail passed through mail.alvarion.com > > **************************************************************************** > ******** > This footnote confirms that this email message has been scanned by > PineApp Mail-SeCure for the presence of malicious code, vandals & computer > viruses. > **************************************************************************** > ******** > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > -- "Speed, it seems to me, provides the one genuinely modern pleasure." -- Aldous Huxley (1894 - 1963) -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
