Does you phone support external antenna? If answer is in positive then buy a roof antenna, hook it at your back and carry it with you. Cut the roof of your car to fit the antenna in car. You will never face low signals issue.
@ altisdualvvti
Like Mifi is different from Wingle? Nope. Both are "Mobile Wifi". The only difference is their shapes and built in battery for one version. Both are powered over USB. Hook your wingle in any USB port even in power bank and there you go, you have internet on the go.
Wingle reception is still a lot better than cell phone. And it has got antenna port too.