According to Nikkei Newspaper, NTT DoCoMo's 2470 base stations are still not functional as of 3/15, 10am, down from 2810 site as of 3/14, 5pm. They say if the rolling blackout continues, fuel may run out at some of the sites and they will stop running.
Ibaragi prefecture is suffering the most, with 80% traffic restriction, followed by Miyagi, Iwate and Fukushima, with 70% restriction.
Michi