nel is a broadcast channel (BC) in the downlink direction and a multiple access channel (MAC) in the uplink direction whose link-level data rates are characterized in terms of capacity regions. Multi-layer SU-MIMO schemes offer layer/stream diversity in the sense that if one stream has a poor SNR, the system will not necessarily experience an outage, whereas in the same situation, a MU-MIMO system will be in outage. This is because in MU-MIMO schemes, users have typically an equal target data rate and symbol error rate on their respective links, while in SU-MIMO systems, only the sum rate of the overall link is considered since all streams are delivered to same user. The MU-MIMO schemes suffer from near-far problem due to significant difference between the path losses experienced by each user, resulting in large deviation in the SINR of the corresponding user links. This would benefit the users with better channel conditions, while there is no near-far problem in SU-MIMO systems. The near-far prob- lem in MU-MIMO systems may be alleviated via appropriate grouping of the users with similar channel conditions. The use of cooperative collocated transmit antennas in SU-MIMO schemes can facili- tate the encoding at the transmitter and decoding at the receiver. In contrast, the users in a MU-MIMO scheme can cooperate in encoding at the base station in the downlink and decoding in the uplink; however, the users cannot cooperate in decoding in the downlink or encoding in the uplink directions. The capacity of the downlink and uplink is theoretically identical in the SU-MIMO sys- tems (given the same transmit power and the perfect channel knowledge in the transmit- ter and the receiver); however, the capacities of the MU-MIMO BC and MAC are not identical. The capacity of the SU-MIMO schemes is less impacted by lack of CSI at the transmit- ter, whereas the capacity of the MU-MIMO BC significantly suffers from lack of CSI at the transmitter. SU-MIMO suffers from limited exploitation of multi-user diversity. The number of sp