Default High cpu temp while using 3g

Hello,
Yesterday I got an LG G2.
When mobile data is turned on and I begin to browse the net or downloading some files, I gets very hot.

The reception is really bad, 1 tick out of 5 when I hold the device in my hands.

I would like to know whether is it normal or not that with low signal and mobile data on the device gets that hot.

I'm attaching a screenshot.
Thanks.