How to calculate DL throughput for LTE category 1

4G LTE
1

Hi experts,

According to TS 36.306 Table 4.1-1,
LTE category 1 : DL 10 Mbps (64QAM, 1 DL layers, bandwidth 20 MHz, other conditions ??? )
LTE category 4 : DL 150 Mbps (64QAM, 2 DL layers, bandwidth 20 MHz)

How to calculate the DL 10 Mbps for LTE category 1 ??
What is the key difference between LTE category 1 (10 Mbps) and LTE category 4 (150 Mbps) ???

Thanks !
Porter Chen