Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1998-05-28
2001-07-31
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S067700, C455S091000, C455S296000, C455S297000, C455S278100, C455S283000
Reexamination Certificate
active
06269090
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to a telecommunication system comprising a first radio system using a first clock signal for defining first channels multiplexed in time, and comprising a second radio system using a second clock signal for defining second channels multiplexed in time.
2. Discussion of Related Art
Such a telecommunication system is of common general knowledge and comprises said first radio system and said second radio system as in for example, well known GSM systems. The first GSM system uses said first clock signal for defining first communication channels multiplexed in time and situated in a first frequency band, and the second GSM system uses said second clock signal for defining second communication channels multiplexed in time and situated in a second frequency band being either equal to said first frequency band or being situated near said first frequency band.
This known telecommunication system is disadvantageous, inter alia, because of said radio systems causing too much interference with each other.
SUMMARY OF THE INVENTION
It is an object of the invention, inter alia, to provide a telecommunication system as described in the technical field, in which said radio systems cause less interference with each other.
Thereto, the telecommunication system according to the invention is characterized in that the telecommunication system comprises a coupling between the first radio system and the second radio system for creating a predefined phase difference between at least one first channel and at least one second channel by adjusting at least one of said first and second clock signal.
Due to the presence of said coupling and the creation of said predefined phase difference as a consequence of said adjustment, the first location of said at least one first channel and the second location of said at least one second channel can be chosen (adjusted) such that interference is at a minimum level.
The invention is based on the insight that said locations of said channels affect their interference.
The problem of said radio systems causing too much interference with each other is thus solved by adjusting at least one of said first and second clock signals via said coupling.
It should be observed that it is of common general knowledge to reduce the interference in two radio systems by introducing a random phase for one of both clock signals. In this case there is no coupling between both radio systems for the creation of a predefined phase difference between both channels as a consequence of an adjustment of clock signals via said coupling.
A first embodiment of the telecommunication system according to the invention is characterized in that said coupling comprises a phase shifting device.
Such a phase shifting device, which receives one of said clock signals and in response generates the other clock signal having a shifted phase, could be located either between both radio systems or inside one of both radio systems.
A second embodiment of the telecommunication system according to the invention is characterised in that said phase shifting device alters a phase of at least one of said first and second clock signals with a constant value.
In this case, the phase shifting device receives one of said clock signals and adds or subtracts a constant value to or from the phase.
A third embodiment of the telecommunication system according to the invention is characterized in that said phase shifting device alters a phase of at least one of said first and second clock signals with a value which is continuously altered in time.
In this case, the phase shifting device receives one of said clock signals and adds or subtracts a value to or from the phase, which value is continuously increasing or decreasing.
The possibility of both radio systems each one having its own clock generator, whereby the coupling is only used for exchanging a control signal for creating said predefined phase difference between said channels by adjusting at least one of said clock signals, should of course not be excluded.
Said coupling between said first and second radio system could, of course, be either a wired one or a wireless one, whereby in the last case for example said second radio system monitors said first channels of said first radio system and derives said first clock signal from said monitored first channels and generates said second clock signal in response to the derived first clock signal by introducing said predefined phase difference.
The invention further relates to a radio system using a clock signal for defining channels multiplexed in time.
The radio system according to the invention is characterized in that the radio system comprises a coupling for a further clock signal belonging to a further radio system using said further clock signal for defining further channels multiplexed in time for creating a predefined phase difference between at least one channel and at least one further channel by adjusting at least one of said clock signal and said further clock signal.
A first embodiment of the radio system according to the invention is characterized in that said coupling comprises a phase shifting device.
A second embodiment of the radio system according to the invention is characterized in that said phase shifting device alters a phase of at least one of said clock signal and said further clock signal with a constant value.
A third embodiment of the radio system according to the invention is characterized in that said phase shifting device alters a phase of at least one of said clock signal and said further clock signal with a value which is continuously altered in time.
The invention yet further relates to a method for providing first radio communication via a first radio system using a first clock signal for defining first channels multiplexed in time, and for providing second radio communication via a second radio system using a second clock signal for defining second channels multiplexed in time.
The method according to the invention is characterized in that the method comprises the steps of
supplying at least one of said first and second clock signal respectively to at least one of said second and first radio system respectively, and
creating a predefined phase difference between at least one first channel and at least one second channel by adjusting at least one of said first and second clock signal.
A first embodiment of the method according to the invention is characterized in that said step of creating said phase difference comprises a substep of altering a phase of at least one of said first and second clock signal with a value.
From DE 32 24 922, Hoefgen (Standard Elektrik Lorenz AG) it is known to delay irregularly information to be transmitted from a subscribing station to a base station. From WO 91/13502 and corresponding U.S. Pat. No. 5,301,188 (Motorola) shared carrier frequency hopping is known. The invention of creating a predefined phase difference between at least one first channel of a first radio system and at least one second channel of a second radio system is known neither from DE 32 24 922 nor from WO 91/13502. All references including further references cited with respect to and/or inside said references are hereby incorporated by reference in their entirety into this patent application.
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Patent Abstracts of Japan 04291831 (Oct. 15, 1992) and Japanese Patent Application 03057301 (Mar. 20, 1991) (Fujitsu Ltd.).
Patent Abstracts of Japan 06164474 (Jun. 10, 1991) and Japanese Patent Application 04317617 (Nov. 27, 1992) (NEC Corp.).
Alcatel
Kizou Hassan
Mehra Inder Pal
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