MIMO and data transmission rate

3.6.2014 Benjamin Gubler
To enhance the rate of data transmission whether it is in office environments or domestic settings, MIMO has been put to use and has given the maximum bandwidth available for client usage. In the 802.11 standard for Wi-Fi and WLAN methods of data transmission, OFDM and MIMO will enable transmission of data reach 600 Mbps at its peak operating level.

The 802.11 Standard allows 4 spatial streams, to improve the available rate of data transmission, because with MIMO various streams of data can be carried over the same channel. As anyone can expect, the overall capacity of data transmission is governed by the number of streams available, which in turn means the number of antennas available at both transmission and receiving ends.

As an example of the rate of transmission in the 802.11 standard, a simple notation, a x b : c is put into use. This equation refers to the antennas deployed for transmission, b to antennas at the receiving end, and c signified the number of spatial streams. This example can be further simplified in the equation 2 x 4 : 2, which means transmission of two antennas which are received by four antennas.

The number of spatial streams remain two, signifying that the receiving and data transmission will be limited to two spatial steams. The 802.11 standard enables systems having 4 x 4 : 4 capability through presently the widely used rate of transmission is 3 x 3 : 3, since throughput is enhanced and thus higher, which is achieved by the additional data stream deployed.

A mode which has been used for optional usage is that to run the system by bandwidth having double sized channels. While the earlier systems made use of bandwidths of 20MHZ it can be double with a frequency of 40MHz, in the new systems using MIMO. This avoids the higher number of channels being used for various other devices in an office environment. Though there may be place for 3 20MHz spatial streams, this system allows for deployment of only one 40MHz channel. Therefore, which one you will use for data transmission is optional.

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