Network synchronisation for UTRA TDD

We present an overview and simulation results for the time and optionally also frequency synchronisation of cells in the UTRA TDD system. The method shown is in the process of being standardised for the Rel-4 in the 3GPP TSG RAN group. It is based on infrequent transmission of special synchronisation bursts over the air interface. The receive timing of these transmissions is measured by neighbouring cells and reported to the RNC (radio network controller), which in turn transmits timing updates to the cells. The overall control lies within the RNC which also computes the receive and transmit schedule for all cells. It is shown that a synchronisation accuracy of 100 ns can be achieved within a start-up time of approx. 400 seconds.