I concur with Scott's idea that you get more efficient spectrum use. We have just installed a Solectek excel link which uses 2x2 mimo. We have a dual polarity 3' dish at one and and 2' dual polarity at the other end of the 14 mile link.
We upgraded an Alvarion VL ptp link which maxed out at about 32mb. This Solectek is advertised as 100+mb, and uses the same 20mhz. We were getting 75mbit using rb433ah as the testing devices while 15-20mbit of traffic was already on the link, and we didn't have the modulation all the way up either. It could go faster if we used PCs to test, used top modulation, used multiple data sources to test, weren't doing it with live traffic, etc... So the testing is very preliminary but the performance is definitely not overstated in this case. So we've effectively tripled our bandwidth over a traditional OFDM link using the same amount of spectrum. We needed the speed right now and didn't want to wait for the UBNT product to be available and mature, and didn't want to be slowed down by a licensing process for a fancier high bandwidth system. Whether it's useful for ptmp depends on the frequency and location. Both polarities are not always available for ptmp use. Sometimes this is so because of interference from other WISPs, sometimes it's due to your own spectrum management where you alternate polarities when the same frequeny is used in an overlapping area but from a different tower. On Tue, Aug 18, 2009 at 10:50:52PM -0400, Scott Carullo wrote: > > Tom, I believe there is a huge advantage to being able to use HPOL and VPOL > at the same time with the same 20Mhz channel and get twice the bandwidth. > Its sort of like your personal gps sync within the device. Realistically > (for me anyway) I find that if there is strong noise on a give channel and > its close enough (same tower / site) than changing the polarity won't help > make the freq usable any way. Therefore I argue that MIMO (2x2) allows for > BH use the actual more efficient use of spectrum. I do not compare that at > all to the same as using two different 20Mhz chunks of spectrum and argue > that you can indeed get twice the bandwidth out of the same 20Mhz (or 40Mhz > if your environment allows) spectrum. > > I'm seeing it right now in my test gear or I'd be a skeptical as the > bunch... I like what I see so far but my testing has been somewhat > limited. I'll know a lot more this time next month. I'm sure this > discussion will do nothing but get more interesting in the near future when > the rubber hits the road. > > Scott Carullo > Brevard Wireless > 321-205-1100 x102 > > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -- /* Jason Philbrook | Midcoast Internet Solutions - Wireless and DSL KB1IOJ | Broadband Internet Access, Dialup, and Hosting http://f64.nu/ | for Midcoast Maine http://www.midcoast.com/ */ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
