Not sure if this is what you are getting at but high speed comms modulate a signal up from a lower frequency to a much higher carrier frequency for transmission. Then the receiver modulates back down to baseband (the original frequency before modulation). This can be done with discrete hardware, no need to do the DSP with a CPU that can't reach those clock speeds. It's one of the reasons your 5GHz WiFi doesn't actually have a 2.5Gbps bitrate (satisfying the Nyquist criterion), but something closer to 1.3Gbps.

Source: graduate with MS EECE in Comms, Control, and Signal Processing in a couple months