The only way to really counter such an attack would be to have a constant stream of traffic going 24/7 that is set at such a level that your normal usage never exceeds it. Then, when you send a real message, the computer throttles back on the garbage communication and injects your real traffic into the stream. The amount of traffic thus remains constant and it would be difficult to do any type of frequency analysis on the traffic.

However, depending on how high the garbage stream must be set to ensure that there is never a spike of real communications higher than that, it could easily be too costly for most people.