Basic MIMO

•Basic MIMO with direct map
–Transmit antenna number is equal to the number of spatial streams
–Utilize identity mapping matrix, i.e. each spatial stream maps to one transmit antenna
•Basic MIMO with spatial spreading
–The number of spatial streams is less than the number of transmit antennas
–Utilize unitary spatial spreading matrix, or typical Walsh matrix
–Utilize cyclic delay diversity (CDD) to improve the performance of transmit diversity; when linearly increasing cyclic delays are applied to the antennas, time-domain cyclic delays can further mitigate undesired beamforming effects