LTE - The Channel quality indicator (CQI)

The Channel quality indicator (CQI) of the definition

• A combination of modulation scheme and transport block size corresponds to a CQI index
• Each PDSCH transport block ((modulation scheme + transport block size)  CQI index)
• Block occupying a group of downlink physical resource blocks  CSI reference resource, received with a transport block error probability (< 0.1).
•  Highest CQI index between 1 and 15 condition, or CQI index 0 if CQI index 1 does not satisfy the condition,
• In the frequency domain, the CSI reference resource is defined by the group of downlink physical resource blocks corresponding to the band to which the derived CQI value relates.
• For periodic CSI reporting, it is an element of the CSI subframe set linked to the periodic CSI report when that UE is configured with CSI subframe sets.
• An OFDMA frame is divided into K sub channels in the frequency domain and T symbols in the time domain.
• In each OFDMA frame there are T × K slots and each UE may be allocated one or more such slots according to its application requirements.
• The slot on the kth subchannel at the tth symbol  denoted as (kth, tth) slot.
• The CQI of the whole frame is perfectly known at the eNodeB through messages from UEs