Mobile network signal issue

So almost after 3 weeks of getting the TS I decided to put in my AT&T SIM. I was reluctant to use that tiny bastard screw driver but I did it anyways. I have noticed that the network signal strength of my watch is almost non-existant. It will get cellphone signal at only certain place. With the same sim card on my phone (Nexus 5), I get good cell reception.

How are others doing in this department? How's the cellphone signal? Is there anything I can do to improve the mobile network signal. Currently I am on stock with Loki's security patch.

I am not sure if this is a hardware issue or software issue. I remember someone opening the TS and checking the antenna. Any suggestions would be highly appreciated.

Some information on my TS -

North American 1/8
Stock ROM with Loki's patch.

Ok here is my observation:

I could not get signal inside my office, home and costco

I did get signal once I get out of my office - full signal bars with H+. I made a short trip from office to costco and home and back to office. It was able to get signals when I was driving but in some areas where I used to get 2-3 bars in my phone, TS did not pick at any signal at all. So mobile network signal is working but it is pretty weak compared to my phone.

May be it needs some tune up