Talk:CQI

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Channel Quality Indicator: Channel Quality Indicator (CQI) is a measurement of the communication quality of wireless channels. CQI can be a value (or values) representing a measure of channel quality for a given channel. Typically, a high value CQI is indicative of a channel with high quality and vice versa. A CQI for a channel can be computed by making use of performance metric, such as a signal-to-noise ratio (SNR), signal-to-interference plus noise ratio (SINR), signal-to-noise plus distortion ratio (SNDR), and so forth of the channel. 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 can be dependent upon the transmission (modulation) scheme used by the communications system. For example, a communications system using code-division multiple access (CDMA) can make use of a different CQI than a communications system that makes use of orthogonal frequency division multiplexing (OFDM). In more complex communications systems, such as those making use of multiple-input multiple output (MIMO) and space-time coded systems, the CQI used can also be dependent on receiver type. Other factors that may be taken into account in CQI are performance impairments, such as Doppler shift, channel estimation error, interference, and so forth.