Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
1999-07-27
2002-11-05
Bost, Dwayne (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S500000, C455S422100, C370S503000, C370S350000
Reexamination Certificate
active
06477385
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a mobile communication system suitable for use, for example, in digital cellular phones and mobile communications of small-zone time division multiaccess, and a method for establishing synchronization in mobile communications.
BACKGROUND OF THE INVENTION
In TDD (time division duplex)-TDMA (time division multiple access) mobile communications, such as PHS (personal handy-phone system), timing of transmission/receiving should be adjusted between a plurality of base stations installed within the service area to prevent the occurrence of interference.
Means, which has hitherto been used, for coping with this demand is such that the standard is set so as to be consistent with that of other device with which the base station is in synchronization, alternatively such that all the base stations are brought to synchronization with one standard station.
When the standard is set so as to be consistent with that of other device with which the base station is in synchronization, however, the management of these devices is likely to be influenced by other devices. Further, in areas where any standard device is absent, it is impossible to provide synchronization between base stations.
On the other hand, when all the base stations are brought to synchronization with one standard system, a lot of time is disadvantageously taken for achieving synchronization in the whole service area.
SUMMARY OF THE INVENTION
The invention has been made under these circumstances, and it is an object of the invention to provide a mobile communication system and a method for establishing synchronization in mobile communications that can ensure synchronization between a plurality of base stations and can enhance frequency reuse in time division transmission without suffering from increased interference.
According to the first feature of the invention, a mobile communication system comprises:
a plurality of first base stations each having a predetermined radio zone, for performing communication with one or more mobile stations;
a plurality of second base stations each having a predetermined radio zone, for performing communication with one or more mobile stations and, in addition, giving a synchronous standard to said plurality of first base stations; and
an absolute synchronous station for giving a synchronous standard to each of the plurality of second base stations.
In the mobile communication system, preferably, the plurality of second base stations each have a predetermined synchronous area and a plurality of the first base stations with the radio zones being in contact with or overlapped with each other are present within the synchronous area.
Preferably, the second base stations each have first timing control means for controlling the timing of a control channel signal transmitted to other second base station based on the timing of a control channel signal transmitted by the absolute synchronous station.
Preferably, the second base stations each have second timing control means for controlling the timing of a control channel signal transmitted to the mobile station based on the timing of a control channel signal transmitted by the absolute synchronous station.
Preferably, the second base stations each have second timing control means for controlling the timing of a control channel signal transmitted to the mobile station based on the timing of a control channel signal transmitted by the other second base stations.
Preferably, the control channel signal has a predetermined fixed code at a predetermined position of all bits, and the second base stations each delay the control channel signal to be transmitted so that the bit position of the predetermined fixed code contained in the control channel signal transmitted is consistent with the bit position of the predetermined fixed code contained in the received control channel signal.
According to the second feature of the invention, a method for establishing synchronization in mobile communication, comprises the steps of:
providing a mobile communication system comprising
a plurality of first base stations each having a predetermined radio zone, for performing communication with one or more mobile stations,
a plurality of second base stations each having a predetermined radio zone and each having a predetermined synchronous area, for performing communication with one or more mobile stations and, in addition, giving a synchronous standard to the plurality of first base stations with the radio zones being in contact with or overlapped with each other within the synchronous area, and
an absolute synchronous station for giving a synchronous standard to each of the plurality of second base stations; and
through each of the second base stations, controlling the timing of a control channel signal transmitted to the other second base stations based on the timing of a control channel signal transmitted by the absolute synchronous station.
In the method for establishing synchronization in mobile communication, preferably, the second base stations each control the timing of a control channel signal transmitted to the mobile station based on the timing of a control channel signal transmitted by the absolute synchronous station.
Preferably, the second base stations each control the timing of a control channel signal transmitted to the mobile station based on the timing of a control channel signal transmitted by the other second base stations.
Preferably, the control channel signal has a predetermined fixed code at a predetermined position of all bits, and the second base stations each delay the control channel signal to be transmitted so that the bit position of the predetermined fixed code contained in the control channel signal transmitted is consistent with the bit position of the predetermined fixed code contained in the received control channel signal.
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Bost Dwayne
Contee Joy K.
NEC Corporation
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