Mazin just suggesting perhaps there is interference near or at Cell 1 and Cell 2 (C1 & C2) determine Cell 2 should be used.
When I conduct radio surveys I use not only one of the following: Sagem, Anritsu or R&S Romes but will also take a number (about five) standard Nokia handsets with netmon switched ON. You be amazed that with 3 Nokia handsets all switched ON maybe one of the three can be camped on different cell to the other two or all three can be on different cells.