New QuadCore 1.3 phone gives low WIFI signal

I recently bought two of this phone model Videocon A55qhd. Both have one common problem low WIFI signal strength. If I keep Videocon A55qhd and old Samsung pocket at the same distance, samsung has much better WIFI signal strength.

In Videocon sometimes only one WIFI signal comes whereas my other phones work perfectly. Please suggest me how to fix this issue?