TechInfoDepot:MIMO

MIMO

• http://www.quantenna.com/technology/

Multiple-input Multiple-Output (MIMO) is a communication method for wireless transmission where both

transmitter and receiver use multiple antennas.

The use of multiple antennas at both sides of the link creates a multi-path propagation environment

between transmitter and receiver that can be used to significantly improve the system throughput.

The origin of the improvement can be intuitively understood by thinking of the multi-path propagation

MIMO environment as the equivalent of several separate paths between transmitter and receiver.

Every one of these paths (or “streams”) can be independently used for data transmission with each

employing the full bandwidth available to the system. This is referred to as spatial multiplexing.

The higher the number of antennas, the higher the multiplexing gain.

In addition, MIMO enables other advanced techniques like beamforming and MU-MIMO.

The higher the number of antennas, the more efficient these techniques become.

MU-MIMO

Multi-User MIMO (MU-MIMO) provides an alternative use of the spatial multiplexing that is provided by MIMO.

MIMO enables the transmission of multiple independent streams between a transmitter and a receiver with

multiple antennas. However, without MU-MIMO, the spatial multiplexing gain is limited by the number

of antennas at the client devices (typically one or two), leaving a lot of spatial diversity unused.

MU-MIMO extends the MIMO concept to the case with one transmitter and multiple receivers (Downlink MU-MIMO)

or to the case with one receiver and multiple transmitters (Uplink MU-MIMO), allowing the full use of the spatial

diversity provided by the channel. Instead of being able to transmit to a single client, an MU-MIMO capable

system can transmit to several clients simultaneously, using the full bandwidth of each link.

802.11a/g

Proprietary MIMO technology can be found in some Wireless-G devices.

However, both the access point and the adapter must support the same technology.

These proprietary MIMO modes are not standardized between vendors..

Most high throughput modes (including some branded as MIMO) do not use MIMO tech.

Proprietary vendor specific MIMO modes, by manufacturer

Airgo True MIMO (Gen1, AGN100) - max. PHY rate of 108Mbps (2x2/2x3),

two spatial streams

• Linksys SRX
• Belkin Pre-N

7 client adapters using AGN1xx, 6Empty strings are not accepted. embedded systems using AGN1xx

Airgo True MIMO (Gen3, AGN300) - max. PHY rate of 240Mbps (2x2/2x3) • PCWordl,

two spatial streams, channel bonding

• Linksys SRX400
• Netgear RangeMax 240

14 client adapters using AGN3xx, 6Empty strings are not accepted. embedded systems using AGN3xx

Atheros VLocity (AR5513) - 108Mbps (two Tx/Rx chains, single spatial stream

[not really 'True' MIMO], channel bonding [Super G / Super AG])

11 client adapters using AR5513, 4Empty strings are not accepted. embedded systems using AR5513

Additional (non-MIMO) proprietary vendor specific modes, by manufacturer

Atheros Super G / Super AG - 108Mbps max. signalling rate (w/ channel bonding)

Super G (wireless networking) on Wikipedia

Broadcom Afterburner (125HSM) - 125Mbps theoretical max. signalling rate

125 High Speed Mode on Wikipedia

• Linksys SpeedBooster

Ralink MIMO XR - 108Mbps (while branded MIMO, RT2661 only supports multiple receive chains..)

• Linksys RangeBooster
• Belkin Wireless G Plus MIMO

36 client adapters using RT2661, 21Empty strings are not accepted. embedded systems using RT2661

Intersil Nitro - claimed ~140Mbps throughput (per Wikipedia)

Nitro (wireless networking) on Wikipedia

802.11n

MIMO is a part of the 802.11n specification. Different notations may be used

to describe the MIMO capabilities of a given device.

TxR:S

• T: Number of transmit radio chains
• R: Number of receive radio chains
• S: Number of spatial data streams

1x1:1 - 150Mbps transmitting and receiving

1x2:2 - 150Mbps transmitting, 300Mbps receiving

2x2:2 - 300Mbps transmitting and receiving

2x3:2 - 300Mbps transmitting and receiving

3x3:2 - 300Mbps transmitting and receiving

3x3:3 - 450Mbps transmitting and receiving

May also be described as xTyR where x is the number of transmit radio chains and y is the number

of receive radio chains. This notation neglects the number of spatial data streams.

• 1T1R SISO - 150Mbps transmitting and receiving (single input single output)
• 1T2R MISO - 150Mbps transmitting, 300Mbps receiving (multiple input single output)
• 2T2R MIMO - 300Mbps transmitting and receiving (multiple input multiple output)
• 2T3R MIMO - Usually 300Mbps transmitting and receiving (multiple input multiple output)
• 3T3R MIMO - 300Mbps or 450Mbps transmitting and receiving depending on the number

of spatial streams (multiple input multiple output)

What is a "Stream" anyway? (how 802.11n works)

Modulations

See also

• List of MU-MIMO supported devices

No QAM

	802.11a	802.11b	802.11g	802.11n	802.11ac	802.11ad	802.11ax	802.11ay	802.11be	Notes
1x1:1	54	11	54	150	433	2160	287/600.5			<-Per stream
2x2:2				300	867	4320	574/1201
3x3:3				450	1300	6480	861/1801
4x4:4				600	1733	8640	1148/2402
5x5:5					2165		1435/3002
6x6:6					2598		1772/3603
7x7:7					3031		2009/4203
8x8:8					3464		2296/4804
9x9:9							2583/5404
10x10:10							2870/6005

16-QAM

	802.11a	802.11b	802.11g	802.11n	802.11ac	802.11ad	802.11ax	802.11ay	802.11be
1x1:1						4620
2x2:2
3x3:3
4x4:4
5x5:5
6x6:6
7x7:7
8x8:8
9x9:9
10x10:10

64-QAM

	802.11a	802.11b	802.11g	802.11n	802.11ac	802.11ad	802.11ax	802.11ay	802.11be
1x1:1						6756
2x2:2
3x3:3
4x4:4
5x5:5
6x6:6
7x7:7
8x8:8
9x9:9
10x10:10

256-QAM

	802.11a	802.11b	802.11g	802.11n	802.11ac	802.11ad	802.11ax	802.11ay	802.11be
1x1:1				200			961
2x2:2				400			1922
3x3:3				600
4x4:4				800	1733		3844
5x5:5
6x6:6
7x7:7
8x8:8							7688
9x9:9
10x10:10

1024-QAM

	802.11a	802.11b	802.11g	802.11n	802.11ac	802.11ad	802.11ax 2.4/5	802.11ay	802.11be
1x1:1				250			574/1201		344
2x2:2				500			1148/2402		688
3x3:3				750					1032
4x4:4				1000	2167		2296/4804		1376
5x5:5
6x6:6
7x7:7
8x8:8							4592/9608		2752
9x9:9
10x10:10

4096-QAM (4K-QAM)

	802.11a	802.11b	802.11g	802.11n	802.11ac (Wi-Fi 5)	802.11ad	802.11ax (Wi-Fi 6/6E)	802.11ay	802.11be (Wi-Fi 7)
1x1:1									2882
2x2:2									5765
4x4:4									11530
6x6:6
8x8:8									23060
10x10:10
12x12:12
16x16:16									46120