5.7 Node B synchronisation procedure over the air

25.2243GPPPhysical layer procedures (TDD)TS

An option exists to use the regular DwPCH transmissions to achieve and maintain Node B synchronisation [20]. This optional procedure is based on measurements of DwPCHs from neighbouring cells according to an RNC schedule. The timing offset measurements are reported back to the RNC for processing. The RNC generates cell timing updates that are transmitted to the Node Bs and cells for implementation (common with the 3.84 Mcps TDD option). Alternatively the RNC may indicate that the NodeB shall autonomously adjust the cell timings. Two distinct phases can be distinguished for Node B synchronisation over the air, with a potential additional sub-phase involving late entrant cells.

5.7.1 Initial synchronisation

Common with 3.84 Mcps TDD, see [4.9.2 Initial Synchronisation], however, the regular DwPCHs are used as cell sync bursts.

5.7.2 Steady-state phase

Common with 3.84 Mcps TDD, see [4.9.3 Steady-State Phase], however, the regular DwPCHs are used as cell sync bursts. If the NodeB adjusts the cell timings autonomously, it shall take into account the propagation delay, signaled by the RNC.

5.7.3 Late entrant cells

A procedure that may be used for introducing new cells into an already synchronised RNS involves the continuous measurement of the DwPCHs of the neighbouring cells by the late entrant cell. The RNC may use this information to adjust the late entrant cell sufficiently to allow the cell to enter steady state phase.