[lxgr]

Yeah, that’s what I mean: They don’t need an absolute time reference; they can just respond with whatever delay/frequency offset compensates for the one observed as they communicate.

S-CDMA did have close timing requirements between cells, as far as I know, but the GSM/3GPP family of standards never did.

[g_p]

TDD networks (where the same frequency is used for downlink and uplink, but with timeslots for each) do need tight timing between cells though, but it doesn't have to be absolute - just in sync with each other so one cell doesn't blast out a full power downlink while adjacent and nearby cells are quietly trying to listen for the (much quieter) uplink transmissions of their user devices.