Proximity-1 Space Link Protocol is a short haul delivery communications protocol designed to establish a two-way communications link between a lander and an orbiter, negotiate data rate and communications mode, and reliably deliver data during short orbiter-to-surface contacts. 
Developed by Consultative Committee for Space Data Systems and documented in a number of CCSDS Recommendations
Proximity-1 is implemented on Mars Exploration Rovers, Mars Odyssey, Mars Reconnaissance Orbiter, Mars Express as well as on Phoenix Mars Lander.
The frequency band used by this protocol is in the 70-centimeter band so as to reduce complexity of the ground craft, using these frequencies:
However, using this protocol over the standard CCSDS frequency bands is perfectly acceptable if the UHF allocation is not usable.
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