For synchronizing user devices to the base station of a 5G or 6G network, the base station can transmit brief prepared signals at a pre-scheduled time and frequency. All of the user devices in the network can then synchronize simultaneously, using amplitude measurements with standard signal processing. The user devices can thereby avoid the complex and time-consuming measurements of prior art. This simplified synchronization procedure may be especially relevant for reduced-capability IoT devices. Examples are provided in which each user device can measure a ratio of amplitudes or energy values in sequential symbol-times as determined by the local user device clock, and compare to the expected ratio as determined by the base station clock. Any deviation in the ratio indicates a timing offset, which the user devices can then use to precisely synchronize the local clock.