ABCDEF频段是怎么划分的

ABCDEF 频段如何划分的，不太清楚，谢谢各位大神

可直接查找规范

a)   1900 - 1920 MHz:          Uplink and downlink transmission
2010 - 2025 MHz  Uplink and downlink transmission

b)   1850 - 1910 MHz:          Uplink and downlink transmission
1930 - 1990 MHz:          Uplink and downlink transmission

c)   1910 - 1930 MHz:          Uplink and downlink transmission

d)   2570 - 2620 MHz: Uplink and downlink transmission

e)   2300—2400 MHz: Uplink and downlink transmission 

f)   1880 - 1920 MHz: Uplink and downlink transmission