MIMO ( Multi Inpit Multi Output )

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MIMO Systems can provide two types of gain:
Spatial Multiplexing Gain and transmit Diversity Gain
In Spatial Multiplexing Gain , maximum transmission rate  can be achieved by sending different  data streams at different antennas
Whereas  in Diversity Gain, maximum quality(QOS) can be achieved  by sending same data streams to different antennas.
There is a tradeoff between  these two gains as spatial diversity can be achieved under good radio conditions where as transmit diversity is done under poor radio conditions to achieve good quality.
System designs are based on trying to achieve either goal or a little of both


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