The access technologies can use advances in
wireless antennas, such as multi-input, multioutput
(MIMO) antennas. For 4G networks, MIMO
is an important technical advance. Figure 6 shows
how single-input, single-output (SISO) antennas
(used in most mobile phones today) and MIMO
antennas work. The MIMO allows either more capacity
(bit rate) or improved quality of transmission
(because the receiver can take the best signal out of
multiple copies of the same signal it receives).