modes is the number of streams transmitted to the user), modulation and coding rate to be used on each layer, power boosting (power boosting values to be used on the data and pilot sub-carriers), and band selection (location of the localized resource units across frequency). The uplink MIMO Mode Selection Precoder Vector/Matrix Selection Resource Allocation MCS/Packet Size ACK/NACK Model Rank/PMI Encoder carrier Resource Precoder Mapping Encoder Antenna Mapping Layers Streams Antenna Ports FIGURE 10-45 Uplink MIMO architecture [2] CHAPTER 10 The IEEE 802. 16m Physical Layer (Part II) antenna configuration is denoted by N X Nr where N 1,2,4 denotes the number of MS transmit antennas and N1 > 2 denotes the number of BS receive antennas. There are two MIMO encoder formats in the uplink: (1) space-frequency block-coding; and (2) collaborative spatial multiplexing (vertical encoding). Uplink SU-MIMO physical processing is similar to that in the downlink. Uplink MU-MIMO is performed through collaborative spatial multiplexing with vertical encoding at each MS. The number of spatial streams in the uplink depends on the MIMO encoder. For open-loop and closed-loop spatial multiplexing SU-MIMO, the number of streams is Ns < min(Nt, Nr), NS < 4. For open-loop transmit diversity, Ns depends on the space-time coding scheme used by the MIMO encoder and the number of transmit antennas at the MS. The MU-MIMO schemes can support up to four spatial streams in the uplink. The number of spatial streams allocated to one user is limited to one, if there is only one transmit antenna at the MS. In that case (N = 1), SFBC encoding is not used at the MS. Vertical encoding with one spatial stream is allocated to an MS with one transmit antenna. Non- adaptive and adaptive precoding are supported on the uplink where non-adaptive precoding is used with open-loop SU-MIMO and open-loop MU-MIMO modes, and adaptive precoding is used with closed-loop SU-MIMO and closed-loop MU-MIMO modes. For non-adaptive precoding at sub-carrier k, the N X NS prec