Dear ahmetemir,
Parameters k and d correspond to slope (k) and intercept (d) of a linear approximation of the BICM (Bit Interleaving and Coding Scheme) curves around the SNR regime relevant for a given CQI (Channel Quality Indicator).
If you are interested in more details about this approximation, the paper: S. Schwarz, Ch. Mehlführer and M. Rupp “Low Complexity Approximate Maximum Throughput Scheduling for LTE”; gives a nice explanation.
Best regards,
Fjolla