What techniques are available for correcting constellation rotation due to phase ambiguity?
In my experience from the space industry, both near-earth and deep-space communication system resolve phase ambiguity by means either unique word detection or different flavors of differential encoding. In unique word detection technique, an "Attached Sync Marker (ASM)"(a.k.a a unique word), a preamble of some sort (usually the hex pattern 0x1ACFFC1D) is attached at the beginning of every frame (known as channel access data unit (CADU)). Now, the receiver rotates the received symbols until the ASM is detected. The diagram below from CCSDS Radio Frequency and Modulation Systems--Part 1: Earth Stations and Spacecraft, page 2.4.11 gives a summary of scenarios for (offset) QPSK where the techniques are more appropriate.


Regards,

Moses.