If you want to download any file at higher speed on the Android platform, by using either the UMTS / HSDPA / LTE connection with WiFi – whichever is currently active just download  Super Download which combine Wi-Fi and 3G to download larger files like HD videos at maximum download speed.

What Super Download Android application does? It combines Wi-Fi and 3G connectivity to maximize your download speed.

The Super Download app is available to download at the developer Elban from the XDA-developers forum and you can even download it from the Official Google Play Store, it’s a free Lite version and a full version that costs 50 cents. Lite version downloads only up to to 50MB data. For some functions, the device must be rooted on which one wishes to use Super Download app.

Super Download developer Elban explains:

Download web files much faster by using wifi and mobile data at the same time!
Share or open a link from any program, like the web browser, and download it at speeds up to two times faster than usual.
This is the only tool that can download using wifi and mobile data connection simultaneously!

Super Download combine Wi-Fi and 3G, so the speed of both connections will be combined & therefore a file can be downloaded much more quickly. This works with all links from a browser or other apps.

Super download is now optimized for Smartphones, but it also works with Android tablets. In order to install this application the Smartphone/Tablet must be rooted. Rooting Android isn’t a big task, as you can easily root your device by using CyanogenMod application which is free to download.

Source: XDA-blog