Ptcl evo 3.1 signal problems!

I have recently been using PTCL EVO 3.1 and was given a Huawei device (white) by the ptcl guys. I am getting low signals during evening, is there any way that i could increase the signals and it seems there's no option to attach an external antenna to the device. So, will i be able to get full signals or say 80% of it, if i purchase a ZTE device(black) which has the option to connect an antenna to it. Btw, does the speed variations depend on the signals or the number of Evo users near the tower???Any reply will be deeply appreciated. Thanks

-ZTE balck dongle has a port for connecting antenna. Old Huawei dongle also had but that model is no longer available. Connecting external antenna didn't seem to work for me with ZTE dongle (Possibly, my antenna was crap). According to the philosophy of ''Best effort basis'', find the place for best signals reception.

-Number of simultaneous users affect the speed in specific area, even distance from tower as well whether you get full signals. Speed depends fully upon signals strength one is getting.

I have posted the solution earlier for areas with week signals.

Use 7 feet long extension cable, I am using it since one last year and its working