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Multiple Input, Multiple Output (MIMO) technology is a wireless technology that uses multiple transmitters and receivers to transfer more data at the same time (Figure 1). MIMO technology takes advantage of a radio-wave phenomenon called multipath where transmitted information bounces off walls, ceilings, and other objects, reaching the receiving antenna multiple times via different angles and at slightly different times.
Figure 1: MIMO Technology Uses Multiple Radios to Transfer More Data at the Same Time
MIMO technology leverages multipath behavior by using multiple, “smart” transmitters and receivers with an added “spatial” dimension to dramatically increase performance and range. MIMO allows multiple antennas to send and receive multiple spatial streams at the same time. This allows antennas to transmit and receive simultaneously.
MIMO makes antennas work smarter by enabling them to combine data streams arriving from different paths and at different times to effectively increase receiver signal-capturing power. Smart antennas use spatial diversity technology, which puts surplus antennas to good use. If there are more antennas than spatial streams, as in a 2x3 (two transmitting, three receiving) antenna configuration, then the third antenna can add receiver diversity and increase range.
In order to implement MIMO, either the station (mobile device) or the access point (AP) need to support MIMO. Optimal performance and range can only be obtained when both the station and the AP support MIMO.
Legacy wireless devices can’t take advantage of multipath because they use a Single Input, Single Output (SISO) technology. Systems that use SISO can only send or receive a single spatial stream at one time.
This applies to:
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