Internet access in Brazil (Rio de Janeiro)

Hey folks,

Am landing in Brazil soon to "try it on for size" for 5 to 6 months with a view to longer term, and an essential requirement for me (for work) is reliable internet access. I know many apartments come with it, but just to cover all eventualities, am I able to get access via either cellphone tethering or USB dongle via any of the mobile services for a reasonable prepaid cost?

Thanks,
Dave