Unhappy [Q] How to Increase Wifi TX power signal strenght in LG L7 II P715

Hi,

I am using LG L7 II P715 i want to Increase Wifi TX power signal strenght for better connectivity, how i can change power.

in my home there are one more phone Samsung s7582 that phone connected wifi. wifi router is on ground flr and mobile connected on 2nd flr but i am using LG L7 II P715 didn't get signal from same place. samsung phone connected nicely and LG didn't why this is happening ??

please give me some solution ......

Thanking You
Pravin