Method of synchronizing base stations of a terrestrial cellular communication network
The present invention relates to a method of synchronizing base stations of a terrestrial cellular communication system using a satellite component.
1. A method of synchronizing base stations of a terrestrial cellular telecommunication network, the network including at least first and second asynchronous base stations,
which method includes the following steps:
a step of said first and second base stations sending to a telecommunication satellite a first message, including a first frame synchronization word and a second message, including a second frame synchronization word,
a step of retransmission by the satellite to a processing device on the ground of said first and second messages, the satellite and the processing device being synchronous with a reference time system.
2. Method according to claim 1 , including a step of transmission by the synchronization device of the cellular telecommunication network to a terminal of the information taking account of said real TOW between the base stations visible from the terminal, enabling the synchronization device to effect a triangulation on the signals emanating from those base stations.
3. The method of claim 1 , further comprising:
the following steps being executed within the processing device:
a step of searching for the first frame synchronization word sent in the message by the first base station,
a step of searching for the second frame synchronization word sent in the message by the second base station,
a step of apparent time stamping T 16a-Reception of the first synchronization word and of apparent time stamping T 16b-Reception of the second synchronization word.
4. The method of claim 3 , further comprising:
a step of calculating the distance between the first base station and the satellite, the processing device knowing the position of the first base station and the position of the satellite,
a step of calculating the distance between the second base station and the satellite, the processing device knowing the position of the second base station and the position of the satellite.
5. The method of claim 4 , further comprising:
a step of calculation, from the distance calculated between the first base station and the satellite, of the routing time T 16a-Routing to the satellite of the first synchronization word from the first base station to the satellite, and of calculation from the distance calculated between the second base station and the satellite, of the routing time T 16b-Routing of the second synchronization word from the second base station to the satellite.
6. The method of claim 5 , further comprising:
a step of calculation of the real Time of Week (TOW) of the first synchronization word and of the real TOW of the second synchronization word, respectively in accordance with the formula T 16a =T 16a-Reception −T 16a-Routing and the formula T 16b-Reception −T 16b-Routing ,
a step of transmission of information taking into account said real TOW from the processing device to a synchronization device of the cellular telecommunication network.