EARFCN DL band lower band while UL band higher band

Hi all,
I am getting one issue while analysing like in DL earfcn most of sample are lower band (700 & 850) & in UL ue many samples are from higher layer aws3.
Site is having only pcs & aws3 carriers.
So can anyone explain explain what might be the reason for this?

Dear all,
Effectively, the general rule in terresterial network mobile, the UL band must be greater than DL band. But for 800 Mhz for example this rule is not respected because the transmitters of broadcasting uses the adjacent band 470-690 MHz and if we did not respect this last rule UL greater than DL band, the LTE UE will interfered by TV transmitter which have a great power.

Any other reason can cause this?