Which Network provider is the best in terms of "Signal" (3G) in Chennai ?

Tweet

I am trying to get a new Simcard for my back up phone, Nokia N70. Backup phone!! Yes, i already own an lumia 1020 and it uses an Airtel network. But i am getting heavy signal drops on my lumia 1020 due to Airtel (i guess) when i am inside my home or at malls (like Phoenix market city, Chennai).. Even i had the same problem, with N70 (Airtel IND).. So i want an Simcard/network provider which provides the "best signal coverage" at almost all places like shopping malls, theater, offices and even an interior homes.. My Location is south Chennai.. Suggest me the best network provider in this category... I DONT need to know the best plans and service.. My first priority is "Signal".. Please Help...