d by making use of performance metric such as a signal-to-noise ratio, signal-to-interference plus noise ratio, etc. These values and others can be measured for a given channel and then used to compute a CQI for the channel. The CQI for a given channel is dependent on the physical transmission scheme used by the communication system. In communication systems which make use of multiple-input multiple-output and space-time coding schemes, the CQI can also be dependent on receiver type, MIMO mode, etc. Other factors that may be taken into account in CQI are performance impairments, such as Doppler shift, channel estimation error, interference, etc. CHAPTER 9 The IEEE 802.16m Physical Layer (Part I) Cyclic Shift ---6 OFDM Symbols ---6 OFDM Symbols ---6 OFDM Symbols BS #1 BS #2 BS #3 FIGURE 9-37 Interlaced pilots structures for two data streams [2] inside an open-loop region are averaged over the open-loop region pilots. For MIMO feedback reports requested with a MIMO feedback mode for operation outside the open-loop region, measurements are conducted on the downlink MIMO midamble. The wideband CQI reports outside the open-loop region (i.e., measurements on MIMO midamble) are averaged over the frequency partition indicated by the Frequency Partition Indicator (FPI) parameter in Feedback Allocation A-MAP IE. For reports requested with a MIMO feedback mode for open-loop MIMO operation, the MS should adjust the non-precoded MIMO channel estimated from the midamble by applying it with the non-adaptive precoder according to the MIMO, the sub-band index, and the MIMO rate. For reports requested with a MIMO feedback mode for closed-loop operation, the MS should adjust the non-precoded MIMO channel estimated from the midamble with an esti- mated adaptive precoder. The sub-band CQI reports inside and outside the open-loop region should be reported for sub-bands in sub-band LRUs indicated by the secondary superframe header. 9.9 Pilot structure and channel estimation 9.9.3 Uplink Pilot Structure Uplink pilots within a logical re