Video stream with Mikrotik boards trout mobile broadband?

Hi,

I want to make 3G or to say „mobile broadband“router that can bond 2 or 4 USB mobile modems and route video stream to CDN. Is there any Mikrotik board that can do that or combination of routers and other stuff?
The key problem is that one USB modem can take up to 3mbps upload but not stable at all times and if I can put 4 different provider modems (or 2 from one provider and 2 from the other) with that amount I can have balanced 3mbps sure.
There are several manufacturers that sell these kind solution products but are very expensive.

Thanks for solutions.