 an adjustment factor proportional to the number of receive antennas at the BS, is a masking parameter which can be set to zero or one to exclude or include nstream effect on SINR target, and nstream is the number of streams in the logical resource unit that is signaled by the uplink Basic Assignment A-MAP IE. When SU-MIMO mode is used, nstream is set the number of streams for the MS. When a collaborative spatial multiplexing mode is utilized, nstream will denote the aggregated number of streams. If the calculated SINR target for the traffic channel higher than the maximum SINR defined in the AAI_SCD MAC control message, the SINR target is set the maximum value. For a traffic channel, the Poffset is set to the value that is signaled in the AAI_UL- POWER-ADJUST MAC control message. Figure 10-20 illustrates the statistical distribution of the IoT with Y as a parameter which is obtained from exhaustive system-level simulations using IEEE 802.16m evaluation methodology general assumptions. Based on the same assumptions, the effect of open-loop power control on the cell edge and cell spectral efficiencies as a function of control command rate and Y is shown in Figure 10-21. It can be seen that slightly higher cell spectral efficiency and slightly lower cell edge spectral efficiency are obtained with slower power control rate. For the uplink control channels, with the exception of initial ranging and sounding, the SINRtarget in Equation (10-20) is set separately for each control channel type, e.g., SINRtarget_HARQ for the uplink HARQ feedback channel. The target SINR for each control channel is signaled through the AAI_SCD MAC control message. The BS may change the mobile station's transmit power by signaling through the Power Control A-MAP. When the MS receives these commands from the serving BS, it updates the control channel Poffset value, based on the power correction value transmitted by the BS. The control channel power offset is initially set to zero until the MS receives the first AAI-UL-POWER-ADJUST MAC contro