I was mostly OK with these (even though VOFDM is BS) until I got to slide 19, where you claim "3-14dB of Gain" from 2-antenna diversity. Not even MRC will generate *14dB* of gain over 2-antennas.
What has BAWUG become, "hawk our proprietary warze?" Geez. Jim Greg DesBrisay writes: > > P.S. > For more detail on OFDM and field tests of (non-802.11) OFDM systems, > please take a look at my presentation on the "Basics of Orthogonal > Frequency Division Multiplexing (OFDM)" at > http://www.ewh.ieee.org/r6/scv/comsoc/0101.PDF or > http://www.wca.org/Year2000/gregdesbrisay.pdf . > > Regards, > > Greg > > > > > > On Thu, 2003-07-24 at 23:00, Greg DesBrisay wrote: > > > > > > Ladjicke, > > > > OFDM is essentially a multi-tone modulation, with some tricks thrown in > > that allows the tones to be closer together than traditional multi-tone > > systems. Imagine a 256-tone OFDM signal; each tone is modulated > > independently; since there are 256 tones the symbol rate is 1/256 times > > the symbol rate of a single-tone system; therefore the 256-tone OFDM > > signal can tolerate 256 times more multipath than a single-tone modem > > without equalization; or alternatively, the 256-tone system can send > > data 256 times faster in a multipath environment than a simple > > single-tone modem without equalizers can. And the OFDM system doesn't > > require expensive processor-intensive equalizers to do so. > > > > So how does this apply to non-line-of-sight (NLOS) communications? > > In NLOS situations the direct signal, if it exists, is greatly > > attenuated, so multipath becomes far more significant than in LOS > > situations. OFDM is excellent at handling multipath, so it is very well > > suited to NLOS communications. > > > > I've set up several OFDM 45-Mbps links in the 5.8-GHz U-NII band over > > distances of about 10 miles with absolutely no LOS--diffracting over > > roof tops, trees, and hills. These links ran for weeks with no packet > > errors. Note: you still have to obey the laws of physics so you have to > > have enough signal at the receiver to detect! For these links I used > > 4-ft dishes on each end of the link. > > > > Different systems have different power output levels, have different > > data rates, have different modulation on the tones, have different > > error-correction schemes, have different adjacent-channel sensitivity, > > and are designed to operate in different frequency bands which have > > different regulations on allowable power output and antenna gain, but > > your question asked about OFDM in general, so this is my general answer. > > > > Criticisms from others about 802.11a on this list don't seem to be > > related to OFDM, they seem to be related to other issues of receiver and > > transmitter design. > > > > I hope this helps! > > > > Greg DesBrisay > > [EMAIL PROTECTED] > > > > > > > > > > > > > > On Thu, 2003-07-24 at 14:26, Ladjicke Diouf wrote: > > > Can somebody shed some light on how OFDM helps NLOS, I thought it was just a > > > coding scheme like DSSS for 802.11b > > > > > > Ladjicke > > > > > > > > > >From: Patrick Leary <[EMAIL PROTECTED]> > > > >To: 'George' <[EMAIL PROTECTED]>, "802.11B NEWS GROUP" > > > ><[EMAIL PROTECTED]> > > > >Subject: RE: [BAWUG] 802.11b Long Range non line of sight > > > >Date: Thu, 24 Jul 2003 11:20:35 -0700 > > > > > > > >No such animal exists. 802.11b is by definition of the technology on which > > > >it is based a LOS only solution (this includes our own 802.11b). For NLOS > > > >you will need an OFDM based bridge, such as those offered by us or a few > > > >others. > > > > > > > >Patrick Leary > > > >Alvarion > > > > > > > >-----Original Message----- > > > >From: George [mailto:[EMAIL PROTECTED] > > > >Sent: Thursday, July 24, 2003 2:16 PM > > > >To: 802.11B NEWS GROUP > > > >Subject: [BAWUG] 802.11b Long Range non line of sight > > > >Importance: High > > > > > > > > > > > >Hi guys, > > > > > > > >I was wondering if anyone had came across with an 802.11b equipment > > > >that doesnt need clear line of sight. > > > >I am tasked of bridging a link for a10mile remote site. But Line Of > > > >sight is not very clear. Can anyone please > > > >suggest what can i possibly do to accomplish this. > > > > > > > >thanks in advance > > > > > > > >George > > > > > > > > > > > >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. > > > >**************************************************************************** > > > >******** > > > > > > > > > > > > > > _________________________________________________________________ > > > Help STOP SPAM with the new MSN 8 and get 2 months FREE* > > > http://join.msn.com/?page=features/junkmail > > > > > > -- > > > general wireless list, a bawug thing <http://www.bawug.org/> > > > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > > > > > > -- > > general wireless list, a bawug thing <http://www.bawug.org/> > > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > > > -- > 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
