indeed, it is confusing 🙂
a “reduced” TSC is used in normal burst, to help the MS fine-sync : thanks to it, the MS is able to extract the useful contents of the burst and perform equalization.
the “long” TSC is transmitted on the SCCH (in the BCCH timeslot), and it is used for almost the same purpose : the MS uses this sequence to be in perfect sync with the timeslot “rythm” of the cell. After listening to the TSC, it knows when is the start and end of the BCCH bursts.
The MS doesn’t “listen” to the neighbour cells, it just “measures” the BCCH level. Once in a whilem it decodes the neighbour BSIC, but it doesn’t try to sync with the neighbours.
During HO procedure, the BSC sends the HO COMMAND to the MS. In this HO CMD, the TSC is indicated so that the MS is able to find the “reduced” TSC located in the middle of the normal bursts of the neighbour cells. This is needed because the MS didn’t previously listened to the BCCH of the neighbour. Therefore, it cannot know the TSC 🙂
I hope it is a little clearer…