A good primer on 802.11n. Beamfroring starts at page 6.
Brough Turner wrote: > As Mike points out, beamforming is an optional part of the 802.11n > standard and there is at least some silicon support for this option > emerging (more on that in a moment). The confusion arises because > there are several different things which are legitimately called > beamforming. > > The simplest is a switched beamformer in which there are multiple > directional antenna elements and the radio is connected to the > appropriate elements as needed. This is what Ruckus Wireless does > today. They have 12 or more fixed elements and on a frame-by-frame > basis they decide which two of those elements to connect to the two > terminals on the Atheros (2x2 MIMO) Wi-Fi chip. A bunch of people > have patents here, but the ideas are very old so the patents may not > be very valuable. > > Next is phased array beamformers. Here there are multiple simple > antenna elements typically equally spaced in an array. Phase delays > are introduced so, via constructive and destructive interference, you > end up with a beam. Then that beam is steered by varying the phase > delays. This is also well established technologies that the military > have been using for (many) decades. > > Finally, in MIMO systems, maximal-ratio-combining (MRC) is doing > receive beamforming in as much as the computation is equivalent to > placing the maximum receive lobe as close to the desired signal while > placing nulls as close as possible to the primary interferers. > > While the widespead 2x2 MIMO chips are primarily used for horizontal > and vertical polarization, 3x3 and 4x4 MIMO chips are emerging. With > 4x4 we can expect to see transmit beamforming via phasing and receive > beamforming via MRC. Indeed, two silicon startups, Quantenna > Communications in California and Celeno Wireless in Israel, have > announced Wi-Fi chips that support 4x4 MIMO with transmit > beamforming. The Quantenna chip is used in the Netgear WNHDB3004. > > The 802.11n standard specifies how the needed information is passed, > so the computations that Quantenna and Celeno (and others in the > future) do can be carried out when devices from different vendors > interoperate. > Thanks, > Brough > > Skype: brough Mobile: +1 617 285 0433 > http://blogs.broughturner.com > > > On 10/26/10 12:37 PM, Mike Hammett wrote: >> http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4558648 >> >> "In the IEEE 802.11n draft standard, beamforming is adopted as an >> optional feature to improve signal reception and simplify receiver design." >> >> Beamforming is available in 802.11N, though I don't know of any products >> using that standard. >> >> ----- >> Mike Hammett >> Intelligent Computing Solutions >> http://www.ics-il.com >> >> >> >> On 10/25/2010 5:15 PM, Faisal Imtiaz wrote: >> >>> Rogelio, >>> >>> Please don't take this the wrong way..... You are trying to understand a >>> very complex 'patented' technology via a very simplistic understanding. >>> >>> Beam forming is a very complex (lots of analytical analysis done on a >>> real time basis) technology, there are a number of Masters& PHD Thesis >>> papers on this topic that you can find by Googling. >>> >>> There is no 'chipset' for it.... Each of the folks you mention utilize >>> 'internally developed' patented techniques of applying the 'Beam >>> Forming" concept. so there is no 'standard'.... the chipset are simple >>> transmitters and signal processors .... (math units..) >>> >>> The beam forming technology works in both direction (sending& >>> receiving)..... There is no such thing as a 'omni' beam forming >>> antenna. The antenna pattern is dynamically changed to focus / lock on >>> to the signal of the CPE that the AP is talking to. >>> >>> Plus, there is NO 'Beam Forming" Standard...and don't expect one in the >>> future..... since it is more of a 'type of antenna design' and not a >>> 'defined formula'. >>> >>> Regards. >>> >>> Faisal Imtiaz >>> Snappy Internet& Telecom >>> >>> On 10/25/2010 5:54 PM, Rogelio wrote: >>> >>>> I see lots of discussion about the new 802.11n standard supporting >>>> beam forming, and I'm trying to wade through the chipset ones (e.g. >>>> Ruckus, Extricom, Meru, etc) and other solutions that claim to be more >>>> standards based. >>>> >>>> >>>>> From what I gather from the marketing literature, the various vendor >>>>> >>>> solutions direct the signal "more efficiently" towards specific >>>> targets (focusing beam in certain direction, monitoring interference, >>>> "interference nulling", etc), but that seems to have limited >>>> effectiveness when it comes to receiving transmitted packets from the >>>> client end (resulting in slow uplink?). In some of these cases, the >>>> receive antennas are just an omni antenna. (802.11 is not a timing >>>> based protocol, so I don't see how beamforming benefits on the receive >>>> side will ever happen) >>>> >>>> So is the best that we can hope for with beam forming is faster >>>> download but the same old upload? How will the standard (once baked >>>> in more vendor gear) do things differently? >>>> >>>> >>>> -------------------------------------------------------------------------------- >>>> 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! 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! 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/ >> >> > > -- > Thanks, > Brough > > Brough Turner > Ashtonbrooke.com > Office: +1 508 915-4788 > Mobile: +1 617 285-0433 Skype: brough > Also: broughtur...@gmail.com > Blog: http://blogs.broughturner.com/ > > > ------------------------------------------------------------------------ > > > > -------------------------------------------------------------------------------- > WISPA Wants You! 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