Just so this doesn't get too far off topic what was being responding to was someone desire to do a 10 mile NLOS path. 10miles pushes the capabilities of almost all part 15 equipment, let alone a NLOS link.
Some links have been posted that claim OFDM is better in a urban environment with strong signals but severe multi-path (I think the link distances cited where 1.5km and 3.0km respectively). I don't question this claim as I also use OFDM for amateur radio, in which multi-path delay can approach 1ms (Pactor 3, MT63 and Q15X25 are all amateur radio OFDM modes). What I am questioning is the claim that OFDM offers better long distance penetration abilities as compared to other data methods. I've no doubt that in a severe multipath environment, with strong signals, it can offer some advantages, I've just seen no evidence a different data method can bend the laws of physics, when multi-path is not a significant player. Now, if you saying xPSK is a more sensitive modulation then X, then just say this. But I question if OFDM, by itself, comparing apples to apples, offers any intrinsic penetration advantages. This is what I am looking for this white paper to answer.... Then again, those that know, already know, so maybe it is time for the moderator to give this thread a well deserved death? -- Jeff King, [EMAIL PROTECTED] on 07/31/2003 On Thu, 31 Jul 2003 06:38:45 -0700, Patrick Leary wrote: >Judd, You are comparing apples to bananas to oranges. I know; I make >them all (DSSS, FHSS, OFDM, and 900MHz). 900MHz produces better >penetration soley as a matter of frequency, not modulation. And if >you had a 900MHz that also did OFDM, you'd learn it would be far >more capable than even my own 900MHz FHSS or anyone else's 900MHz >DSSS. > >You are welcome to think OFDM is "useless." You should know though >that every major WLAN company disagrees, as do the engineers in the >IEEE. 802.11a is OFDM based. 802.11g is OFDM based. 802.16a is OFDM >based. Within 2 years, you'll have a very difficult time finding any >DSSS in WLAN world. The consensus is all there that OFDM represents >the core of the next generation. Even Aperto, Proxim, Airspan, and >others historically resistant to it, have now said OFDM will form >their core products. > >As for UWB, no one with any knowledge would disagree that it is am >extremely capable technology and can do all the best of everything. >You neglect the reality of the regulatory environment. The FCC >barely approved what minimal version they did. It matters not one >wit what something can do if the feds do not permit the technology >to be implemented to maximum effect. > >Lastly, you should be candid with this community and admit your >visceral hatred of all things Alvarion. Lord knows I have the >collection offlist threats and attacks from you over the past 2 >years. It is also why no positive Alvarion comments or Alvarion >people are allowed on his "uncensored" list. That is also why Judd >will always take a position contrary to my position, regardless of >its intellectual merit. > >Comments about our being proprietary are silly to the absurd. In >almost every standard to date you'll find us as part of the core >team creating it. In wireless broadband, there was no standard to >implement. EVERY vendor building specific for wireless broadband had >no choice but to implement "proprietary." There was no standard to >implement. Now there is with 802.16a and where is Alvarion? We were >in 802.16a in the begiunning. We are chiefly the ones responsible >for creating harmonization between ETSI HiperMAN and the 802.16a >(which was a very tough battle our scientists won that is key to >industry adoption going global). Oh, and we hold the number 2 and 4 >positions (VP and Treasurer) at WIMAX. And we announced with Intel >just a few weeks ago that we will be the first to use their >standards-based 802.16a silicon. > >Alvarion, Motorola, Proxim, Trango, Aperto, Airspan, Navin, >Beamreach, Cambridge, Netro, Hybrid, Vyyo, P-Com, Western Multiplex, >Malibu, Arraycom, Waverider, WiLAN, Redline, and the few others I >missed...they all have proprietary products at the moment. Now that >is an inconvenient fact isn't it? > >As for affordability? It is true, you find us too expensive. >However, most of the market of legitimate operators disagree. Ours >books are public. Examine them for yourself for the proof by >comparing our results to any and all of our peers. > >- Patrick > > >-----Original Message----- From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] Sent: Wednesday, July 30, 2003 11:08 >PM To: '[EMAIL PROTECTED]' Subject: Re: [BAWUG] 802.11b Long >Range non line of sight > > >With DSSS and FHSS, you don't need LOS either. But there are >extreme limits on distance and when it comes to getting links on a >sectored or omni directional ptmp system, your going to be hit-and- >miss. > >>From what I've heard, the 900Mhz stuff works well, very well, NLOS >>like we >see on our cell phones, where a general wall or building isn't going >to kill your signal to an unusable amount. But at 2.4Ghz and >5.8Ghz, even with OFDM and AP's that cost $2500+ each and $600-1000 >CPE, your not going to only battle hit-and-miss coverage, but then >you begin the battle price vs widespread acceptance of the >technology. > >UWB might be the next big step, where, instead of a complete loss of >a connection, you only lose part of the connection that is blocked >and the throughput may fall, but may still be usable at 100Mbit of >sustained throughput, even with error rates. > >Personally, I think that OFDM is useless unless it becomes >affordable. Alvarion has never brought equipment down to a generally >affordable level, in contrast to other existing equipment solutions. >So I don't have much faith in anything that Alvarion claims, even if >it is true and does work, cuz we don't want to go broke implementing >proprietary solutions that give no consideration to current market >demands, including price requirements for acceptance. > >By widespread acceptance, I mean that at some point, the equipment >would become fairly "standard" for the industry. > >Judd > >Jeff King wrote: > >>Thanks Patrick. What I am looking for is the "white paper" that >>will >qualify >>your statement: "With OFDM, you DON'T need LOS." in the context of >>the >title >>of this thread (or at least the frequency domain). >> >>-- Jeff King, [EMAIL PROTECTED] on 07/29/2003 >> >>On Tue, 29 Jul 2003 17:15:04 -0700, Patrick Leary wrote: >>>Until I can link to our paper, here are some resources to study >>>OFDM. >>> >>>http://www.palowireless.com/ofdm/tutorials.asp >> >>-- 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 > > >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 -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
