Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Patent
1995-05-12
1998-09-15
Urban, Edward F.
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
455524, 375356, H04B 700
Patent
active
058094261
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to an arrangement for producing, in mobile telecommunication systems which operate with base stations transmitting to mobile units, a central synchronization of the transmitters of each respective base station, taking into consideration propagation time delay, delays in the cabling, transmitters and so forth.
The invention is also of the type which operates with information-receiving elements, a real-time clock and comparing elements.
Base stations operate in mobile radio communication systems with coverage areas. When the coverage areas partly overlap one another or interfere with one another, a manual or automatic synchronization process is used. In automatic synchronization systems, it is usually a base station the internal clock of which is assumed to be reference clock, a master clock. The base station which is provided with the master clock then carries out a sequential synchronization of the internal clocks, slave clocks, of the other affected base stations. Using a reference time signal, transmission takes place from the affected base station which operates with the reference clock, the master clock. The signal is received in the regular receivers of the other affected base stations which receivers adjust their internal clocks to the reference time. After that, the synchronized base station establishes communication with a new base station which is then synchronized to it, and so forth. The base station which is provided with a reference clock function/master clock function is frequently arranged with an atomic clock.
In connection with mobile systems belonging to this category, a plurality of methods have been proposed for synchronizing the transmitters in the base stations. The methods have included synchronization of single base stations or parts of the transmitter network.
SUMMARY OF THE INVENTION
Today's modern mobile telecommunication systems presuppose that the mobile units can flexibly move within the total propagation range of the system at the same time as the greatest possible attention can be paid to the mobile units being located within areas, where the coverage areas of one or more base stations overlap one another, when it is of highest priority that the base stations are synchronized with one another with respect to time.
It should be possible to carry out this synchronization in such a manner that the synchronization is effected at the same time in all transmitters of the base stations which are to be synchronized on the occasion in question. Furthermore, the synchronization should not occupy channel resources in the mobile system. It should be possible to carry out the synchronization in such a manner that the synchronization effects influences on/adjustments of the internal real-time clocks with which the base stations are operating. The invention is intended to solve the abovementioned problems, among others.
In one embodiment of the subject matter of the invention, an internal real-time clock is utilized in the base stations, which clock should be able to be allocated a standardized time or be referred to such a time. This time should be the same for all transmitters of the base stations in the total system. The invention is intended to solve this problem as well.
In one embodiment of the subject matter of the invention, a common time information is utilized, which is transmitted from a central coordinating unit. It should be possible for this time information to consist of a standardized time signal which should be referred to a standardized time or consist of such a time. The invention also intends to solve this problem. In one embodiment of the invention, it should be possible to compensate for a time delay which is produced in the station S itself. The invention is also intended to solve this problem.
In one embodiment of the invention, it should be possible to synchronize the total coverage area of the whole mobile telecommunication system. The invention is also intended to solve this problem.
In one embodiment of the invention,
REFERENCES:
patent: 4696052 (1987-09-01), Breeden
patent: 4742514 (1988-05-01), Goode et al.
patent: 4850032 (1989-07-01), Freeburg
patent: 5404575 (1995-04-01), Lehto
Carlsson Staffan
Nilsson Goran
Radojevic Milan
Telefonaktiebolaget LM Ericsson
Urban Edward F.
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