when a subscriber changes LAC, its mobile will trigger a location update procedure. This procedure takes place on the SDCCH channel.
– too many LACs will increase the amount of load on the SDCCH channels of the cells at LAC borders. This can lead to SDCCH congestion on the border cells, but also overload the BSC.
– locating a LAC border in an area where a lot of people are moving in and out, it will generate additional Location Update procedures.
– not enough LACs, meaning the size of a LAC is large, this might create paging problem : the subscribers locations is known at the LAC resolution, so when receiving a call, the MSC as to page for the whole LAC. Too many subs in a LAC : too many Pagings.