Synchronization method for radio transmitters in a local e.g. nationwide paging network

Claim 1

A synchronization method for radio transmitters in a local, e.g. nationwide paging network, said paging network being connected to a public switched telephone network and comprising in the transfer sequence of paging messages: - a paging network unit (PNU), provided with means for receiving, processing and transmitting messages in digital form as well as means for manual feeding of network-related parameters, - transmitter site interfaces (TSI) which have a data communication connection to the paging network unit (PNU) and which have means for receiving, processing and transmitting messages in digital form, - base station radio transceivers (Tx, Rx), whose transmitters (Tx) under the control of the above controllers transmit radio signals intended both for paging and for synchronizing the base stations covering a common overlap area, characterized in that said synchronization method comprises the following actions: a) a paging network unit (PNU), which is common to base stations, is used to set up a synchronization plan, including - determination of a synchronization route - choice of a base station to start the synchronization - determination of route-linked identifier for each base station - determination of distances between base stations along the route b) a paging network unit (PNU), which is common to base stations, is used to send to transmitter site interfaces (TSI) via a data transmission network a synchronization command which according to said synchronization plan includes - information about whether the command-receiving station is the startmr of synchronization or not - a route-related identifier, on the basis of which a station to be synchronized identifies and accepts only a synchronization signal received via the determined route - information about the propagation delay of a synchronizing signal c) a synchronization signal is transmitted from the transmitter of a base station chosen as the starter of synchronization in accordance with the synchronization command d) the synchronization signal is received on the receivers of base stations within the reception range thereof and identification information in the received signal is compared with the information given in the synchronization command e) if the comparison of paratraph d) indicates that the received synchronization signal is intended for synchronization of the receiving base station, the clock/signal transmitter of a receiving base station is synchronized to the synchronization signal, f) the transmitter of a base station determined as the starter is switched off and the transmitters of just synchronized base stations are switched on for transmitting the synchronization signal of a second synchronization sequence, g) the synchronization of base stations to be synchronized during the second synchronization sequence is performed according to paragraphs d) and e) with such addition, however, that a synchronizing base station's own receiver receives a signal transmitted by the same station and prior to transmitting the actual synchronization message the phase of a signal to be transmitted is corrected, i.e. shifted forward in time to an extent that corresponds to the sum of delays created in transmitter and receiver and the propagation delay given in the synchronization command, h) a required number of synchronization sequences are executed until the last base stations have transmitted a synchrnization signal that is no longer received on other base stations but the only task is to correct the phase of the clock/signal transmitter of that very station for compensating for the propagation delay and the delay developed in the transceiver.