Thanks. Very clearly in my eagerness I missed that your key point was the long distance.
- Patrick -----Original Message----- From: Jeff King [mailto:[EMAIL PROTECTED] Sent: Thursday, July 31, 2003 5:55 PM To: Patrick Leary; '[EMAIL PROTECTED]' Subject: Re: [BAWUG] Jeff's specific OFDM question about long distance Patrick, take a look at what you responded to in the original thread. You where a first person responder to someone who wanted a 10mile 802.11b NLOS link. To this, you stated: "For NLOS you will need an OFDM based bridge". Immediately after this I asked to see your white paper supporting this claim, and throughout this I have repeatedly reminded you this request was in the context of the title of the original query and question. ("802.11b Long Range non line of sight" > 10 miles) It is all on the list (as well as comments from others). Lets just walk away from this calling it a misunderstanding, OK? It wasn't my intent to embarrass you here.... I had hoped you would catch this mis-speak yourself OR your knew something I didn't. Neither was the case. OFDM does in fact have some very good applications, but doesn't break the laws of physics for long range links which are signal limited. Even so, this does not take away from the excellent applications your products can be used for.... but B is not A Regards, Jeff King wb8wka extra class ham license General Radio Telephone license w/Radar Endorsement Member- ARRL HSMM 802.11b working group P.S. I had hoped to see a white paper that discussed Fresnal Zones and how lower data rate subcarriers help reduced the impact of this or as Tim Pozar suggested, some paper that discussed Knife edge refraction or even bouncing off distant buildings or water towers. Instead, all I have seen are discussions of short range OFDM in urban canyons, with significant signal strengths (I think one paper mentioned -72dBm). Certainly good applications of OFDM, but hardly could be considered long range linking in the context of the thread. -- Jeff King, [EMAIL PROTECTED] on 07/31/2003 On Thu, 31 Jul 2003 13:15:39 -0700, Patrick Leary wrote: > >Jeff, I never claimed here or elsewhere that OFDM, or anything else >for that matter, will provide excellent "long distance penetration >abilities" (which I take to mean long distance NLOS results). If I >did, I'd like to see where, because there is no way I would have >ever intended to imply such. > >Even your offlist mails to me never specified that you were holding >me to some claim about long distance NLOS. > >My claims specifically refer to link paths within the sphere of what >the U.S. wireless broadband might consider a typical cell - say >about 5 miles. In an urban setting, cell sizes are always smaller, >as a natural consequence of a much denser population relative to >system capacity. Accordingly, it is not uncommon for urban cells to >extend no mmore than about 3 miles - regardless of the capabilities >of the technology. It is simply a capacity issue at that point. > >I do say that within those typical 5 miles or urban 3 miles, OFDM >will provide MUCH, MUCH, MUCH better coverage of the footprint than >DSSS or FHSS, and somewhat better than single carrier as well (we >make that too - our WALKair lines use that). > >That's all I contend, though I contend that is very significant >because it means a much higher of potential revenue is now >accessable by your system. So far, any of our DSSS or FHSS customers >have been shocked by the improvements in "connectibility" of once >unreachable prospects and link stability using OFDM. > >It is also true that we do have examples of 6 mile plus links with >zero LOS, but the advantage of knife-edged refraction off the >obstructing ridge, achieving exceptionally stable links netting out >22Mbps. We have plenty of such stories and no way could these same >links be made with anything else in our stable, including our very >good outdoor 802.11b bridge or our FHSS bridges. How do we know? We >tried. > >Kind regards, > >Patrick -- general wireless list, a bawug thing ><http://www.bawug.org/> [un]subscribe: >http://lists.bawug.org/mailman/listinfo/wireless 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
