Hi Pix,
I initially thought the neighbour LACs were sent as part of the serving cell’s system information, but after a little research (after your observation/question), I now believe they’re sent on the neighbours’ SI.
The only LAC info in the SI is found in SI TYPEs 3&4, and this gives info about the LAC of ONLY one cell (the serving cell).
The MS also reads the system information of the six strongest neighbouring cells at least once every 30 seconds( at least to decode the BSIC), and I’m sure it can read the neighbour’s LAC and other parameters during this time.
Let me know what you think.
Regards,
SHELDON