Here you can find the linux driver for MediaTek (Ralink) 7630 wifi card. This version builds under kernels 3.5 - 3.16 (inclusive).
If you are a kernel developer, feel free to fix this driver up and push it to mainline kernel. The code is put here so someone can pick it up, and you are more than welcome to do so, since I don't have time and hardware so please don't expect any improvement.