the MS sends measurement reports in UL.
this message is a list of measurements
DL RxLev of the serving cell : 0 = -110dBm, 63 = -47dBm (or more)
then all the neighbours :
index (= 1 to 6) ; BSIC(i) ; DL RxLev(i)
the index is defined by the BSC for each neighbour, for example, cell A is the serving, cell B and C are neighbours. The BSC send in DL (in the SACCH SI2) the list of neighbours and their index :
cell B BCCH = 47 ; index = 1
cell C BCCH = 51 ; index = 2
the index is actually the position of the cell in the neighbour list.
The MS does not report the Timing Advance to the BSC, it is the BSC that sends the current T.A. to the MS (in DL).
Be sure to look at the correct message, it sounds like you are looking at DL messages…