| 摘要 |
Coarse timing information is distributed 304 from base stations (102, figure 1) to mobile devices (100) using conventional signalling techniques indicating a propagation delay (timing advance commands). Prior to transmitting fine timing information it is determined that the propagation delay between the mobile device and base station is constant 306, i.e. the mobile device is stationary. Accurate measurements of propagation delay (fine propagation delay) are taken (utilising Sounding Reference Signals, SRS, 307). The difference between the coarse and fine timing advance is calculated and quantised, 308. Fine timing information is communicated to mobile devices using the fine timing information to modulate a carrier signal (a series of timing advance update commands 309). The modulation format is such that the average value of the carrier signal is not affected by the modulation. Setting of a clock at the mobile device is based at least in part on: the coarse and fine indications of propagation delay 304, 309, downlink frame timing and System Frame Number SFN alignment to a reference time 301, and a time signal indicating absolute time communicated to the mobile device 302. For the distribution of timing information in an LTE cellular network. |
