Jayson, First off, I'm primarilly a Trango shop not a Moto shop, so I have not BIAS to Moto. We have evaluated Moto Advantage, along with other manufacturer OFDM gear in our attempts to find solutions for faster speeds, for next generation needs. To date, we have found PtP to be the answer for us. But the search for a better PtMP product is ongoing.
Once again I will say, my comments were based on "noisy" environments, and on "efficiency per mhz wide of spectrum used". Two polarities counts as two channels. That in no way was meant to diminish the value of the features Ubiquiti could offer for appropriate situations for the product line. The bottom line is... physics are physics. In my world, the noise floor averages -70, and I don't think I have a single sector on my network that has both the verticle and horizontal pol on a single channel available, and the odds are even lower that I could find two adjacent 20Mhz channels to combine, that would not interfere with myself.. And it should also be noted that most of the noise floor is generated by others' TDD type gear that constantly transmits carrier, so using free time to transmit is not an applicable factor to avoid interference. This is one of the reasons during our Pre-Wimax testing 5 years ago, we abandoned OFDM and Dual pol diversity PtMP set ups offered by WiMax, in favor of Trango 10mb PtMP on the fly selectable polarity solutions. We needed polarity isolation as a core interference rejection method to survive. The pre-wimax gear was lucky to pull of 1.5 mbps, after adjusting to noise, in many cases. Today when we do OFDM PtMP, we only do it in select situations and cubby holes that are adequately isolated to allow it, or as we expand to more rural areas with less congested spectrum. For us, a -97 db receive sensitivity does absolutely nothing for us when there is a noise floor of -70. There is not a single place on our network with a noise floor lower than -80. Our mentality is, even if -97 can be used today somewhere, its just a matter of time before the noise grows to prevent it, thus not a safe long term business model. My beef here is that MIMO marketing is popping up all over the place with misleading ads, that disclose lab results, leaving out the reality of what is required to accomplish the speeds they specify. I have yet to find a technical reason why MIMO yields higher throughput per mhz. And I'd be interested in hearing any factual scentific explanation of why MIMO can achieve more. In our study of Mimo, a few years back, the technical benefits of teh technology were clear in an indoor environment. These benefits were shown with multiple antennas even ALL of the same polarity. The reasoning was that signals received were addative, allowing for higher gain to be realized. (and also some benefits for multiple transmitters but taht is a more complex conversation that this thread). This was best accomplished in an indoor environment where there were MANY diverse reflections. And as a result MIMO added RANGE/Distance, or the ability to get higher modulations because RSSI was better to achieve that. But it did NOT increase efficiency per mhz to achieve higher MAX possible speed. As well, the benefits of recieve combining is drastically reduced in outdoor environments were there are less reflections and narrower beam antennas. That is all physics, and has nothing to do with a preferring a product line. Again, I'm open to any discussion from any opf teh mimo vendors to explain what MIMO adds that allows it to beat the physics of 802.11A, but when I read the manuals from the manufacturers, I just see channel and polarity combinding to reach higher speeds, and they downplay the fact that you need to disable Non-LOS benefits, to achive the speeds. For example, they might discuss better NON_LOS or distance can be achieved by using polarity diversity to send the same data, but then that gives the same speed as a single 802.11a channel, except uses twice the spectrum since two pols are taken, and actually making it half as efficient as 802.11a. Then in the next sentance say it can do double the speed of 802.11a, because it can send different data across each polarity, but take attention away from the fact that inceased range NLOS is not longer going to occur, and that two polarities are being used to get the higher throughput, which is equivellent to taking up twice the spectrum. I also should be clear that I am talking about 2 x2 Mimo, which yields less benefits than a MIMO with more antennas. I can accept the misleading adds for PtP systems because it is more likely that with narrow beam PTP antennas that free spectrum might be able to be found, expectially in rural America. But I'm not buying the case study for PtMP, at least not yet. I could possibly see MIMO as an option to reduce infrastructure needs. For example, if there was only enough spectrum ofr 6 single pol sectors, qty 3 120 sectors with w/ 2 pol Mimo MIGHT be ble to deliver that same capacity as qty 6 non-mimo, if the channel availabilty managed to work out. But it would be at a penalty of less flexibilty of which channel could be used where. The other areas I see MIMO PtMP could possibly work better than non-MIMO is in 5.4Ghz. MIMO's range extending benefit could be extremely useful for low power 5.4, which other wise was range limited, where it has 250Mhz of available clean spectrum to pick channels from. But here, I'd think 3x - 4x MIMO more useful. Another thing worthy to re-investigate is spatial diversity benefits. In the past this has been pushed aside because the minimal increased performance benefit may not have justified the higher costs, with true cost to having multiple antenna, whether it be colocation cost , purchase cost, or simply space. However, now that smaller and cheaper antennas and higher power radios are being made, the performance of spacial diversity may become cost justified. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Jayson Baker" <[email protected]> To: "WISPA General List" <[email protected]> Sent: Tuesday, August 18, 2009 7:44 PM Subject: Re: [WISPA] Bullet M5 HP > MIMO (especially dual-pol) gets you much better performance. Cell phone > companies have been doing this for years and years. > > You're 3dB vs 25dB comment is misleading. UBNT may need a received level > of > -70dBm to achieve higher speeds... but, so does a Canopy. You can't > expect > to achieve anything on a Canopy with, say, a -97dBm signal. Furthermore, > UBNT will actually link around -95dBm and work, albeit slow. Canopy will > say "SCANNING" > > We have tested these products, and have networks deployed both here in the > states and in Costa Rica. You wouldn't think it, but Costa Rica has > waaaaaaay more noise than we do here. The government uses 2.4 and 5GHz > for > random things, people have way overamp'ed equipment, there are a ton of > little WISP's, etc. Canopy down there performs as expected... a couple > mbps > up, a couple mbps down. UBNT MIMO blows it away, especially with AirMax > and > in a noisy environment. > > When testing the MIMO you can't just run a single stream, they work best > with many streams. We have seen about 130Mbps on a full-duplex on a > deployed link, around 15 miles, in a noisy environment. With the PtMP > equipment, we see similar results. With the older non-N non-MIMO > equipment, > we have seen up to 100+ subs on a single PowerStation AP, all getting at > least 12Mbps/6Mbps, and latency always under 10ms. > > I get it, it's a Motorola list. We're on here because we use some of that > too. Not much, anymore, because there are much better products out there. > I'm sure this will start a flame war, as talk of anything other than > Canopy > always does, and I don't really care. The equipment is cheap enough, if > you > want to see it for yourself buy some and put it in. When you see it works > as well as we've seen, you, too, can offer your subs 12Mbps for $25/mo and > make killer profits. Our ROI on a new install is 1 Day. We make money > the > day it's installed. And it just works, we never have customers calling to > complain. > > Cheers! > > On Tue, Aug 18, 2009 at 5:07 PM, Tom DeReggi > <[email protected]>wrote: > >> Yeah, but its misleading garbage specs. >> >> Mimo adds very little in noisy environments, where double size channels >> and >> both polarities can't be both used based on spectrum availabilty, not to >> mention specifying gross speed instead of actual speeds. >> >> I'm not saying the Ubiquiti isn't a really nice needed product, I'm just >> saying, in real world use, I'm not certain its faster than Motorola >> PtMP, >> including advantage series. (per Mhz wide channel efficiency). Don't >> forget >> the 3b SNR required by canopy and the 25db snr required by Ubiquiti for >> high >> modulations, which is rarely acheived in PtMP. Remember, a flaky >> packetlossy link is going to bring TCP down to its knees in throuhgput >> reduction. >> >> The most exciting thing about teh new product is its inferred that there >> might be a low cost dual pol sector antenna available now? >> >> Tom DeReggi >> RapidDSL & Wireless, Inc >> IntAirNet- Fixed Wireless Broadband >> >> >> ----- Original Message ----- >> From: "Paul Hendry" <[email protected]> >> To: "wireless" <[email protected]> >> Sent: Tuesday, August 18, 2009 11:59 AM >> Subject: Re: [WISPA] Bullet M5 HP >> >> >> > Anyone had a chance to fully test any of Ubiquiti's claims like >> > 150+mbps >> > "real" throughput and 300+ subscribers per AP? Much more impressive >> > numbers than Canopy. >> > >> > >> > >> > Matt wrote: >> >>> Ubiquity has introduced their new product lines, at www.ubnt.com. >> >>> Looking to take Canopy on. >> >>> >> >> >> >> Anything like GPS sync for frequency reuse? >> >> >> >> Matt >> >> >> >> >> >> >> -------------------------------------------------------------------------------- >> >> 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/ >> >> >> > >> > >> > >> -------------------------------------------------------------------------------- >> > WISPA Wants You! 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