I concur, Patrick hit the nail on the head with his response. 802.16e has little value with current 3.65 rules, and 802.16d likely a better match..
One of the failicies is that 802.16e means smart antenna designs, which does not have to be the case. Just because many 802.16d vendors favor cost and avoid multple antenna designs, does not mean its not capable in the spec. For example, Antenna diversity techniques to extend range and increase NLOS capabilty is possible. I can tell you Aperto pre-wimax was one of the first to deploy Diversity antenna to increase coverage and link budget. Back in the day, it probably yielded 25% better coverage, although it may not have been often deployed due to cost justification of the solution, based on technology costs back then. But, Michael indirectly brings up a good debate topic, that many WISPs might be looking at today, "Mimo versus WiMax.". A year ago, WiMax was full of products limited to 7-10Mhz channels, claiming spectral efficiency, ignoring real world noise floors. In 5.8Ghz, this led our company to favor non-WiMax products, that supported full 20Mhz channel. However, the world is changing. There are numerous 802.16d products in 5.8G that support 20Mhz channels. I can give an example of the Libre line product (older version was Wi-LAN) sold by Pulsewan. But whether we are talking a 20Mhz channel in 5.8G or a 7Mhzchannel in 3650M, the same challenge is being faced.... "How do I get more speed/capacity per sector in the real world?". When it comes to WiMax, 802.11d is a clear winner over 802.16e, because 802.11d is more spectral efficient. Based on basic radio designs, it can also be argued 802.16d or other TDD polling methods will do better than legacy standard CDMA that will have lower layer1/2 efficiency. But the question today is, what about Mimo? Will Mimo do MORE for speed capacity? Currently, many manufacturers' MIMO designs are limited to diverse dual polarity configuration, which doesn't necessarily have much more spectral efficiency, if you consider a single Polarity a usable channel. Meaning requiring Channel 1 H and channel 1 V, is equivellent to two channels. In an Urban environement opposite polarity isolation can be key to avoid noise floor, and rare to get free channels on same polarity.. These Dual Pol MIMO do however lower cost both for equipment and colocation to reach higher capacity, since two polaries, wider channels (if available) will only take up one mPCi slot and one colocation antenna mount point. But at the end of the day, colocation space is not a limited supply like Spectrum is. Ultimately Spectrum efficiency will become number one importance, expecially when we are crying, "we need more spectrum". Where MIMO gets exciting is in "two same single Pol antennas" designs. Technically, MIMO is made technically possible by diversity in time space. With MIMO, and two antennas, it should be possible to get "Double the speed" in the same amount of spectrum and same single polarity. When match MIMO matched with efficient TDMA, this could potentially give MIMO systems a large spectral efficiency jump ahead other non-Mimo systems such as 802.11d, and even things like Canopy new OFDM solutions. Because 802.11d is a defined standard for interoperabilty, its not likely 802.11d compliant products will evolve to MIMO double capacity designs anytime soon. If WiMax-D manufacturers are doing this, I'd like to learn more about their plans and capabilty. So here is the delimna and hesitation...... Will Single Pol dual antenna MIMO work in the real world to yield higher capacity? It works in the lab because it only considers the RF signal of the link being testing. Surely, diverse time space is free and clear in a controlled environment, to be effective. But in the real world there are other interference sources, that transmit at sporatic time intervals. If two spaces in time are being used for one's signal, there could be double the chance that one of those time periods will line up with an another interference source's time of transmission. Will MIMO be more succeptable to interference in high noise environments, expecially in URBAN America? In broadband its not just about radio raw speed, it is more about TCP throughput. Link quality is more important than link capacity to deliver faster TCP throughput. Let me address it from another perspective... A year ago, prior to low cost wifi availabilty of MIMO.... WiMax had a strong justification, regardless of price. Simply put, spectrum was limited, opportunity was great, and any technology that delivered better survivabilty and capacity spectral efficiency would likely be able to cost justify the technology, even if 10x the cost in some cases. But in today's world, there is a different justification.... Wifi MIMO has the promise of HIGHER capacity. Now WISPs are asking, "What wifi technology compromises am I willing to deal with and accept in order to also have the highly valuable higher spectral efficiency that MIMO might deliver?" Its possible that Wimax-D might not be the leader in spectral efficiency anymore. At minimum, I can argue that MIMO systems will clearly be putting the price pressure on WiMax vendors, or for that matter any Vendor stuck on legacy single stream RF designs. I'd argue MIMO in 3650 could be very attractive even if in Dual Pol config, simply because there is so little spectrum, and starting new, the RF community could be made to conform to dual pol designs easier. I can tell you, I personally will not pass judgement one way or the other on this topic. What I will say is interesting new dynamics are being explored, and we are "testing" technology. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Patrick Leary" <ple...@apertonet.com> To: "WISPA General List" <wireless@wispa.org> Sent: Tuesday, December 29, 2009 3:44 PM Subject: Re: [WISPA] Wimax gear > Why is your basic criteria .16e with MIMO (or .16e at all)? > > All .16e gets you in 3.65 GHz is much more (30% more) latency, less > throughput per MHz, higher overhead and more cost. And you won't get any > hope for interoperability, indoor modems, USB dongles or PC cards, since > those are only applicable to licensed bands. > > > Patrick Leary > Aperto Networks > 813.426.4230 mobile > > -----Original Message----- > From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On > Behalf Of Michael Baird > Sent: Tuesday, December 29, 2009 11:22 AM > To: WISPA General List > Subject: [WISPA] Wimax gear > > We are looking for some more wimax gear to test for the 3.65 band, our > basic criteria would be 802.16e/mimo, we've tested Alvarion gear > already. We are looking for something that will work in an urban > environment with self install radios, can deliver voice and if possible > with PPP/NAT/DHCP in the radio rather then as an external gateway > device. If any dealers out there would like to chime in or hit me off > list I would appreciate it. > > Regards > Michael Baird > > > ------------------------------------------------------------------------ > -------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > ------------------------------------------------------------------------ > -------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > > > -------------------------------------------------------------------------------- > WISPA Wants You! 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