Channel quality information (CQI) is a part of channel status information (CSI). If the channel information is a scalar value such as $ h $, general CQI is the power of $ h $ divided by the power spectral density of the noise, i.e., $ |h|^2/N_0 $ when the noise spectral density is assumed to be $ N_0 $. On the other hand, if the channel information is represented by a vector such as $ \mathbf{h} $, CQI is the norm of the channel vector divided by $ N_0/\alpha $, i.e., $ \alpha ||h||^2/N_0 $, especially when open-loop transmit diversity transmission schemes are used where $ \alpha $ the performance loss factor of the transmit diversity system.