Multiplex communications – Communication over free space – Repeater
Patent
1996-09-19
1999-08-24
Pham, Chi H.
Multiplex communications
Communication over free space
Repeater
370350, H04J 306
Patent
active
059433264
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for synchronizing a telecommunication connection in a mobile communication system, which comprises at least one base station, which communicates on control and traffic channels of the mobile communication system, the uplink and downlink frequencies of said channels being divided into frames containing time slots; at least one mobile station communicating on a direct mode channel divided into frames containing time slots, which mobile station has synchronized its transmission with a basic synchronization converging with the synchronization of a control channel of the base station; a repeater station, which forwards traffic between mobile stations communicating on the direct mode channel and the base station; in which method the repeater station receives a connection set-up request for establishing a telecommunication connection from a mobile station communicating on the direct mode channel to the mobile communication system, and in which the repeater station receives traffic channel information concerning on which traffic channel of the mobile communication system the telecommunication connection to be established must be established.
BACKGROUND OF THE INVENTION
The present invention relates to the field of mobile telephone systems. A subscriber in a mobile telephone system, i.e. a subscriber station, for instance a radio telephone or a mobile station, may be registered in a radio network or a radio system, whereby it is connected to the radio network via system channels comprising control and traffic channels maintained by the base stations of the radio network.
In addition to the system channels provided in mobile phone systems, so-called direct mode channels can also be used in connection with a radio system, i.e. direct mode operation is applied. Subscriber stations using direct mode operation do not communicate directly with the radio network or its base stations. Direct mode channels are frequencies at which mobile phones or other means of communication are able to communicate directly with one another without the system, or via repeater stations, either with the base stations of the system or with other mobile stations.
Direct mode channels are typically used in situations where for instance a group of portable mobile phones are communicating with one another at such a long distance from the base station that system channels cannot be used.
Another important way of using direct mode channels is to increase the capacity when the traffic in the system increases rapidly, e.g., due to occurrence of an incident in some part of the service area of the system, for instance in some point-like part.
A direct mode channel is referred to with the terms direct or simplex channel, or a simplex connection. A direct mode channel is a channel which is typically not at all used by the system. It may be, for instance a channel with the same channel spacing as the channels of the system, for instance 12.5 kHz or 25 kHz. Among the mobile phones operating on a direct mode channel, the transmitting station has tuned its transmitter to the direct mode channel and transmits speech or data information. The other mobile phones set to direct mode operation have tuned their receivers to the same direct mode channel, whereby they are able to directly hear the transmission.
Operation on a direct mode channel may take place on an analog or digital modulation principle. A mobile phone transmitting on the channel may also transmit signalling information, such as information on rights of use and priorities or on a group operating on the channel, or data traffic. On the direct mode channel, an encryption may be carried out or plain speech can be transmitted.
Subscriber stations using direct mode operation communicate with other subscriber stations on a direct mode channel without being in direct contact with the base stations of the radio network. The subscriber stations using direct mode operation can, however, communicate with the radio network via repeater station
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Nokia Telecommunications Oy
Pham Chi H.
Yao Kwang B.
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