MIMO

MIMO

MIMO is multiple input multiple output, MIMO is a technology that is most commonlhy used these days in Wi-Fi and Wi-max technologies (refer to wimax technology in the blog) .

In MIMO multiple antenna are used at transmitter and receiver end. MIMO takes the advantage of multipath transmission.

MIMO can effectively enhance the data rate , range and reliability of the link by sending same data on multiple stream or by sending multiple data on multiple stream at same frequency .

Most of the wireless devices these days have the feature of adaptive switching between MIMO A and MIMO B  ( MIMO A and MIMO B will be discussed at the end of article).

In earlier SISO technology the signals arriving through different paths may cause distructive interference or multipath interference so the efforts was made to receive the signals arriving from direct LOS only and suppress the signals arriving from other paths , which is nothing but the wastage of power.

MIMO technology has effectively utilized the multipath signal reception for its advantage with minimum power wastage.

MIMO with OFDM has made the Wi-Fi and wimax technologies highly spectrum efficient these days.

MIMO 2*2  means 2 antennas at receiver and 2 antennas at transmitter , it increases the spectrum efficiency by two times.

Max channel capacity in MIMO can be defined by  

Channel capacity   = B log _{2 ­}(1+ M*N*SNR)

 Here

B is channel bandwidth.

M is number of antennas at transmitter

N is number of antennas at receiver.

SNR is signal to noise ratio in the link.

Channel capacity is maximum amount of data that can be carried by the cahannel.

MIMO A :  MIMOA comes in use when the overall SNR is low , It tries to maintain the link reliability and coverage by sending same data on multiple antennas.

MIMO B :  MIMO B comes in use when the overall signal strength is high , It increases the capacity of the link bt transmitting different data on multiple antennas.







                                              


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