TX1 carrier board layout


We are designing a PCB with TX1 module. I am looking at the carrier board for reference. I observed, there were no components placed under the chip and bottom side of PCB where TX1 mounted, except in one corner.

Was that done to purposefully to avoid cross talk or something?

Else it was left empty because of height restriction? but I was wondering about the bottom side of PCB being empty.

Please clarify me ASAP as I need to finalize the board size of our project. Also share the specific layout guidelines.

No components placed under module is due to thermal and height limits. The empty bottom side is not must.
Layout guidelines are all in OEM Design Guide, you can download in download center.