Access Point Radio Chain Nomenclature

When we checking access point specification, we always come across “2×3:2”, “3 x 4:3”, this represent MIMO radio design and spatial streams (MIMO mean multiple input, multiple output)

Wireless Radio Chain

Lets define a common nomenclature used on the access points and for that matter on all access points sold today.
For this example we’ll show the Ruckus R700 circuit board.The R700 is defined as a 3×3:3 dual band access point.

What exactly does this mean? On this access point each frequency band (5 GHz or 2.4 GHz) has three radio chains, and each of these radio chains is connect to an antenna.

The first three means that this access point has 3 transmit radio chains. In the R700 for example, these are connected to three 5GHz antennas, 2 vertical and 1 horizontal, and three 2.4 GHz antennas, 2 vertical and one horizontal.

The second “3’ means that there are also 3 receive radio chains for each band.

The third ‘3’ means that there are 3 spatial streams associated with each band, one for each 5 GHz antenna and one for each 2.4 GHz antenna.

The number of streams is a property of the radio chipset and it will vary depending on the chipset manufacturer. Assuming a clear signal, a three spatial stream link will achieve three times the throughput of a single spatial stream in the same channel. For 802.11ac, the PHY rate is 433 Mbps/stream. For 802.11n in the PHY rate is 150 Mbps/stream.

The actual rate can be less due to packet overhead, and air-time efficiencies such as multiple clients trying to access the channel at the same time.

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