Aruba uses Atheros radios, and they aren't software-limited, but rather hardware-limited. That means that their (and everyone else's) radios will have to be upgraded in order to support 3 spatial streams.
The third radio can be used in various ways, e.g. for a 3rd receiver in MRC to make reception more robust and using algorithms such as Cyclic Shift Diversity (CSD) for transmit gain smoothing. There are others, but the net effect is modest on transmit, but decent on receive. Devin K. Akin Chief Wi-Fi Architect Aerohive Networks E: de...@aerohive.com That is my understanding as well. I believe if a vendor’s AP has a third antenna, it can provide some diversity in that the two best of the three can be used at any given time for the two available spatial streams on receive. I have no idea though, how much of a real benefit that translates to in practice. Pete Morrissey From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Marcus Burton Sent: Wednesday, August 11, 2010 4:32 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Band Steering? The Aruba 120 series APs are 3x3 (3 TX x 3 RX radio chains), but they are software-limited to 2 spatial streams. The number of radio chains is not always proportional to the spatial stream capabilities. Marcus Burton Dir. Of Product Development CWNP For the 120 – you sure? On their documentation they show 3X3. We don’t have any 120’s or 121’s, just 60’s 61’s 105’s, 124’s and 125’s, so I can’t say from a testing perspective. From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Ryan Holland Sent: Wednesday, August 11, 2010 2:14 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Band Steering? Just to add clarification, both the AP-120 series and AP-105s only support two (2) spatial streams, despite the additional antenna on the AP-120 series. FYI. ========== Ryan Holland Network Engineer, Wireless Office of the Chief Information Officer The Ohio State University 614-292-9906 holland....@osu.edu On Aug 11, 2010, at 4:01 PM, Greg Williams wrote: Ethan, sorry to not be of much help, but we've never had a problem with Band Steering. We have a pretty dense deployment so maybe that's why. But one thing you mentioned is you are using AP 105's. I can't remember 100% but I did see a degradation in signal using the 105's on 5ghz vs 2.4ghz vs. AP 125 when in a classroom, walled type environment. The AP 105's only have a 2X2 spatial stream not a 3X3. We are using the AP 105's in more open areas for that reason and 125's in the classroom type environments. Greg Williams IT Security Principal University of Colorado at Colorado Springs -----Original Message----- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Ethan Sommer Sent: Wednesday, August 11, 2010 1:30 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] Band Steering? We are upgrading part of our network using Aruba AP-105s and a pair of 3600 controllers. We've found an annoying problem when we have band steering turned on. We've create two SSIDs. Lets call them BandSteering and NoBandSteering. When users are relatively close to an access point, they can connect to either. My MacBook will usually connect using 2.4 Ghz on NoBandSteering and will always connect using 5ghz to BandSteering. When a user is further away from the access point, however, they can connect fine to NoBandSteering (obviously it is slower than when they were closer) but can't connect at all to the BandSteering SSID. It doesn't fail back to 2.4ghz, and the clients don't recognize that they can't connect and connect to NoBandSteering if that's lower in their preferred networks list. The effect is that, understandably, users will select the NoBandSteering SSID because it is more reliable. (Even though it is slower in most cases.) Aruba suggested that I try setting the 5ghz ARM profile to always max out the 5ghz radio, which helps some but does not eliminate the areas where 2.4ghz works and 5ghz doesn't. So, my questions are: 1. Are people using band steering? 2. Have you found the same problem? 3. Is there a way to fix it? (Other than turning off bandsteering.) 4. I suppose a related question is, is there a way to make client computers prefer 5ghz more? I guess we'll probably just not use band steering if we can't find a solution, but it would be a shame not to better utilize the 5ghz spectrum better. Thanks for any suggestions! Ethan -- Ethan Sommer Associate Director of Core Services Gustavus Technology Services somm...@gustavus.edu 507-933-7042 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- BEGIN-ANTISPAM-VOTING-LINKS ------------------------------------------------------ Teach CanIt if this mail (ID 1073089699) is spam: Spam: https://antispam.osu.edu/b.php?i=1073089699&m=6beced56b784&c=s Not spam: https://antispam.osu.edu/b.php?i=1073089699&m=6beced56b784&c=n Forget vote: https://antispam.osu.edu/b.php?i=1073089699&m=6beced56b784&c=f ------------------------------------------------------ END-ANTISPAM-VOTING-LINKS ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
