This probably applies throughout the ranks/awards/unlocks. But here is an excerpt from a recent interview:
Many wonders how the ranking will separate itself from the original game, will it be split into two?
The ranking will be the same, we will use the same system, that you build up on your points, however with the expansion you will get special unlockable weapons and awards that others cannot get. Vi don't want to separate the playerbase, our goal is to keep the community as one instead of spliting it.
If you before the expansion have a certain rank, will you get to keep it or are you forced to restart?
You continue from your current rank and if you already have a very high rank you can even get unlockables directly since you have worked your way up in advance. I don't have the exact points in my head, but there is some room to play even for the high ranked players.
When you install and play the expansion you continue to build on your current profile. As you advance in rank you will gain access to weapons from the expansion to use in BF2. This means that there are no unique unlocks in the expansion but you unlock the possibility to use weapons from the expansion in the original game.
Source