Talk:MIMO

Untitled
I have reverted this article to the original form. MIMO can be a system analysis or a signal processing technique. The original article talked about the signal processing technique but the redirection pointed to the signal analysis. I think this way is better. I posted a comment in the Signal analysis page without response. --Ncc1701zzz 11:33, 15 Apr 2005 (UTC)

Why is:


 * "Other new enhancements will include the arrival of 802.11e and 802.11i. 802.11e will prioritize important information on the network (i.e. a voice message takes precedence over email or a webpage). 802.11i will give an increase in security by using WPA2."

in there? It has nothing to do with MIMO.

Can somebody add something more for MIMO. ??

This following paragraph sounds like a cheap plug for Airgo and Raleigh:

"In 1996, Greg Raleigh and Gerard J. Foschini invented new approaches to MIMO which increased its efficiency. Greg Raleigh is the founder of Airgo Networks, which claims to be the inventor of MIMO OFDM, offering a "pre-N" chipset called "True MIMOTM". However, it is unlikely that hardware based on this chipset will be compatible with other devices once the 802.11n standard is ratified."

I agree that Foschini was very influential in MIMO early development. Raleigh's name doesn't belong in this context and neither does Airgo Networks. Has Wikipedia become a place for cheap advertisement?

A FAQ link should be added to external links. Have both devices be MIMO to have an increase in throughput or just having a MIMO base station is enough?

Answer: MIMO is a characteristic of the radio channel, thus both the radios must have multiple antennas in ordr to be ture MIMO.

Title
MIMO has at least two meanings in Electrical Engineering: MIMO Control and MIMO Communications. Avoiding ambiguity is much more important than avoiding the abreviations. This page is about MIMO Communications and the current title is a wrong title for it. The title should be MIMO Communications orMultiple-Antenna Communications. Bidabadi 00:34, 7 March 2006 (UTC)


 * Call it something like Multiple-input multiple-output (communications) instead, then. This is more in keeping with how we usually name such articles. You'll also need to make Multiple-input multiple-output (disambiguation) and link there to the two articles you referenced on my talk page. Do they both exist? -Splash talk 00:41, 7 March 2006 (UTC)

250Mbit real troughput is more than 10 times higher
250Mbit real troughput is more than 10 times higher than classic 802.11g with its real 25Mbit. For SuperG (40MBit) it is more than 6 times higher. And, speaking of Atheros past expectations for SuperG technology (up to 70MBit theoretical maximum, unapproved) it is just about 3.5 times higher. 802.11 article says the expected maximum is 540Mbit, while manufacturers state it's 650Mbit or 12x speed of 802.11g (in wich they mean higher than 10 times of real 802.11g, and wich is definitely not true as we've seen in previous standard's evolution). That statement definitely needs more approval or is arguable. --GrAndrew 06:39, 4 June 2006 (UTC)

Removing some of the 802.11n stuff
I removed alot of 802.11n discussions since MIMO is much more than just 802.11n. I also statrted to edit the encoding of MIMO where a general approach was taken with linear precoding. We can continue to add decoding algorithms and different precoders etc
 * You did put it somewhere else, right? It doens't need to removed the encyclopedia wholesale. -Splash - tk 15:19, 14 June 2006 (UTC)

This MIMO page needs a major revision
As the suggestion above states, we need to focus less on 802.lln (that has its own entry) and more on MIMO theory. We need to differentiate MIMO from Smart Antennas. What does everyone think about the following outline:


 * Introduction: how MIMO is exactly defined and how it differs from simple smart antennas
 * Early research on possibilities: for example Winters and Paulraj
 * Early Capacity Results: for example Teletar
 * Diversity techniques and space time codes
 * Spatial Multiplexing
 * MIMO technology in the past, present and future: what has and will be built in real systems
 * to include these items, new pages are greatly recommemnd, then I'll contribute as well with items such as More MIMO (Advanced Bemafomring) and More than MIMO (Network or multiuser MIMO)technology JSK 13:08, 15 October 2007 (UTC)
 * References

Obviously this is just a first draft, later we can include tradeoffs between diversity/multiplexing, linear dispersion codes, MIMO receivers, etc.Rcd247 05:46, 12 July 2006 (UTC)
 * This is certainly a classical approach to MIMO writing. One could 'easily' write a textbook or, in my case, an entire thesis on MIMO, though, so I think the challenge is in not doing that, and working out what actually needs to go in each of those sections in this article, and what can be spun out to more detailed articles. The stuff you leave to later is a set of good candidates for their own articles. On the other hand, I already wrote space-time code and its subsidiary articles (to varying depths e.g. space-time block code). Splash - tk 16:23, 9 November 2006 (UTC)
 * Hi, my name is Hermann Lipfert, I'm the author of the 1st reference you mentioned:
 * Lipfert, Hermann (August 2007). MIMO OFDM Space Time Coding – Spatial Multiplexing, Increasing Performance and Spectral Efficiency in Wireless Systems, Part I Technical Basis (Technical report). Institut für Rundfunktechnik.The link behind has gone because of a business failure of IRT GmbH in 2021. So I would like to give you a new link to my private Cloud at GMX_Germany:
 * https://c.gmx.net/@324463044354643784/OvLanXWBTXiRLRtxhIcUww
 * Here you can download the pdf-File!
 * If there are any questions please contact me at my email-address: lipf@gmx.de 2001:A61:A8B:A201:2537:FA5A:26B6:826D (talk) 11:58, 24 April 2023 (UTC)

http://ieeexplore.ieee.org/iel5/49/26726/01192168.pdf states that Winters was not the first to suggest MIMO would increase capacity
 * Actually, on page 283 the authors say "However, to our knowledge, the first results hinting at the capacity gains of MIMO were published by Winters in [8]". Splash - tk 16:23, 9 November 2006 (UTC)
 * Look, people are going to dispute who was the first to come up with MIMO. In terms of array processing, (SIMO, MISO), that stuff was around for a long, long time.  We shouldn't tab somebody as the founder, because, in fact, nobody knows.  Paulraj will claim he was and Winters will do the same. rcd247 11:48, 13 October 2007 (UTC)

MIMO 2.0/3.0
Do anybody have a reference which actuallu uses these classifications (2.0/3.0)? I have never heard of them before. Mossig 18:47, 22 September 2007 (UTC)

I added this term (MIMO 2.0/3.0) to show the important similarty between new MIMO techniques (MU-MIMO and CO-MIMO) and new Web techniques (Web 2.0/3.0). As web 2.0/3.0 are new web trend which calls open, participation, share and intellgeince, MU-MIMO and CO-MIMO are new MIMO techniuqes to improve the system througput by utilizing the other user resources cooperatively and intelligently. So, is it all okay to introduce MIMO 2.0/3.0 to represent its current trend easily JSK 01:29, 23 September 2007 (UTC)


 * In my view this makes it OR and thus not fit to be included in Wikipedia. When (and if) the terms starts to be commonly used it can be reinserted. Mossig 08:28, 23 September 2007 (UTC)


 * Ok, I agree to remove the subsection of MIMO 2.0/3.0 since it is not yet common terminology. However, as it was noted before, why don't we add it inside contents which describes the future MIMO techniques.JSK 12:23, 23 September 2007 (UTC)

I have removed this. It is invented terminology. Interesting terminology, but invented nevertheless. It needs to appear regularly in academic literature before it appears in Wikipedia. Analogies don't belong, unfortunately. tk 23:10, 26 September 2007 (UTC)

MAIMO and variants to be removed
I am not aware of this terminology. Please justify this with citations to academic literature, or it will have to be removed. I have looked on Google and on IEEEXplore and cannot find any references to it, interesting as it is. Splash - tk 23:13, 26 September 2007 (UTC)

Illustration confusing
The illustration on the top right is confusing, or more correctly - confused. Where it says SIMO, it is in fact MISO, and where it says MISO it is SIMO!
 * The terminology refers to the radio channel, and thus the figure is correct as it is.Mossig 18:51, 9 November 2007 (UTC)
 * The problem with the picture is that it doesn't indicate what the "system" is. A block needs to be drawn encompassing the transmit antennas, the receive antennas, and the space between, but not the devices.  This is needed because if the "system" is viewed in subsections, where subsection 1 is just the transmit device and its respective antennas and subsection 2 is just the receive device and its respective antennas, then the MISO and SIMO cases would be incorrectly termed, as multiplexing/demultiplexing occurs at the respective transmitter/receiver accordingly. This stems from the fact that MISO, SIMO, SISO, and MIMO can refer to any system.  Mojodaddy (talk) 21:34, 6 November 2008 (UTC)


 * Almost correct: the antennas are commonly not part of the "system", SISO etc. refers to only the channel. Mossig (talk) 18:19, 10 March 2009 (UTC)
 * So we should draw the box around the radio channel and write SISO, SIMO, etc. inside the box. It is still confusing as confirmed by the comments further down on this talk page. —Preceding unsigned comment added by 69.38.192.210 (talk) 15:43, 9 December 2010 (UTC)

If the digram is indeed correct, I think an explination in the text is in order... At first glance it appears wrong so an explination as to why it is right would be helpfull. MK
 * The text about SIMO etc. is correct in the article, and in correspondance with the picture. Mossig (talk) 18:19, 10 March 2009 (UTC)


 * The current illustration is not very helpful. It merely depicts the schematic differences between MISO, SIMO, SISO, and MIMO (which is obvious and not very informative). The reason that MIMO is an important part of advanced wireless standards is that it exploits multipath propagation to send multiple signals and, consequently, multiply capacity. What's needed is a diagram that illustrates that. A few more diagrams could be added to the article to illustrate multi-user MIMO, massive MIMO, and cooperative MIMO.Claudeb (talk) 23:08, 21 January 2015 (UTC)

Illustration confusing confirmed
I confirm diagram do not match names. SIMO and MISO diagrams are inverted. —Preceding unsigned comment added by Alexandre.2.beaudry (talk • contribs) 14:36, 9 March 2009 (UTC)
 * No, see text above. Mossig (talk) 18:20, 10 March 2009 (UTC)

I understand the text above, but confirm that the image is confusing. I needed to read this discussion page to understand the image. A clearer caption would be helpful, e.g. including "Note the terms 'Input' and 'Output' refer to the radio channel carrying the signal, not to the devices having antennas." 10:14, 23 June 2009 (CDT)

There are many equations using superscript "H"; It seems those should be superscript "T" indicating Transpose. —Preceding unsigned comment added by 209.234.187.194 (talk) 21:45, 8 April 2010 (UTC)


 * The superscript "H" denotes Hermitian transpose, that is transpose and complex conjugation. I have clarified this in the text. —Preceding unsigned comment added by 89.160.7.172 (talk) 20:04, 23 May 2010 (UTC)

Language needs work
This article really needs help from native English speakers. The content might or might not be good, but the language is super-clunky (it falls below the credibility threshold).

"Up to now,[when?] multi-antenna MIMO (or Single user MIMO) technology has been mainly developed and is implemented in some standards, e.g. 802.11n products." "Recently, the research on multi-user MIMO technology has been emerging." "Spatial multiplexing techniques makes the receivers very complex" "a transmitter sends multiple streams by [using? through?] multiple transmit antennas" —Preceding unsigned comment added by 204.15.64.155 (talk) 23:25, 15 September 2010 (UTC)

Introduction could be better
The introduction language could be better. It gets far too technical. Content is fine, just that as-is it needs an introduction to the introduction.67.167.106.3 (talk) 19:18, 17 April 2013 (UTC)

"(pronounced my-moh by some and me-moh by others)"
Surely this could be re-written, sticks out like a sore thumb. — Preceding unsigned comment added by 63.239.86.1 (talk) 01:38, 17 January 2014 (UTC)

Intro confusing
'MIMO is the use of multiple antennas at both the transmitter and receivers'

Ok.

'Note that the terms input and output refer to the radio channel carrying the signal, not to the devices having antennas'

But you just said that MIMO (an acronym basically consisting of the words input and output) refers to the use of 'multiple antennas', and now it has nothing to do with antennas? Well, you lost me.

I also don't see at all what the picture is supposed to illustrate. Antennas, or what? If so, there sure is a lot of mentions of antennas that (according to this talk page) seems to be pretty irrelevant when talking about the concept of MIMO (whatever it might be). — Preceding unsigned comment added by 193.13.114.130 (talk) 00:21, 20 February 2014 (UTC)

Article confused and poorly written
As others have noted, this page has major problems. The biggest is that it confuses what I would call "schematic MIMO" with modern MIMO. I changed the Intro to highlight why MIMO has become an essential element of standards beginning with 802.11n. I've started to correct and clarify the History of MIMO section. There are also problems with the page due to poor writing. Claudeb (talk) 17:08, 28 September 2014 (UTC)


 * I've revised the lead to focus the article on MIMO as the term is used today. I'm also revising the history section which is very unclear. The papers from the 1970s explored methods for overcoming mutual interference (crosstalk) in cable bundles. SDMA is a related concept, but the early patents described methods for frequency reuse. This needs to be explained. Papers on beamforming or that were published in 1999 seem out-of-place. Claudeb (talk) 20:56, 21 January 2015 (UTC)


 * I replaced the diagram at the upper right. The original diagram merely illustrated four possible antenna configurations for a point-to-point link. The new diagram illustrates how MIMO uses multipath propagation to multiply link capacity. This is the operating principle behind modern MIMO and it was nowhere to be found in the original diagram. I will add another diagram when I get a chance to illustate multi-user MIMO. Claudeb (talk) 16:11, 25 February 2015 (UTC)

Daveburstein (talk) 09:47, 21 January 2017 (UTC) I reorganized to give Paulraj credit as inventor and added the link to his Marconi Award page. The $100,000 Marconi Prize is the most prestigious in communications, chosen by a distinguished board. They reviewed the claims of precedence and determined that Paulraj deserved the prize as inventor.

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Question about Frequencies Bands
1. I would like to ask about Frequencies Bands where MiMo is not possible, nor profitable.

2. And I also would like to ask about Frequencies Bands where MiMo is especially possible, easy and profitable.

3. I would like also to ask about how MiMo could prevent some level of Radio jamming and could facilitate Triangulation 4.

(I understand that answer could be negative, but I want to read elaborate answer what would be level (5) of prevention, and what would be level (6) of facilitation).

I would like that answer to these 6 questions would take separate section within article. — Preceding unsigned comment added by 46.187.193.21 (talk) 18:17, 4 April 2022 (UTC)