Telecommunications – Carrier wave repeater or relay system – Portable or mobile repeater
Reexamination Certificate
1997-11-20
2001-01-30
Hunter, Daniel S. (Department: 2749)
Telecommunications
Carrier wave repeater or relay system
Portable or mobile repeater
C455S012100, C455S427000, C455S428000, C455S429000, C455S430000
Reexamination Certificate
active
06181913
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to a method for establishing a connection in a satellite system comprising at least one base station for transmitting and receiving electromagnetic signals, at least a first terminal for transmitting and receiving electromagnetic signals, at least a second terminal for receiving electromagnetic signals and at least one satellite with a transponder for receiving electromagnetic signals and for retransmitting the received signals, with the frequency of the retransmitted signals being shifted with respect to the received signals.
This invention further relates to a satellite system comprising at least one base station for transmitting and receiving electromagnetic signals, at least a first terminal for transmitting and receiving electromagnetic signals, at least a second terminal for receiving electromagnetic signals and at least one satellite with a transponder for receiving electromagnetic signals and for retransmitting the received signals, with the frequency of the retransmitted signals being shifted with respect to the received signals.
Such a satellite system is known per se. In these known satellite systems, such as the inmarsat satellite system, it is necessary to seek contact with the base station in order to file a request to establish a connection. For high-speed data links such as are used for digital video and digital audio connections, this requires special carrier waves operative in duplex mode via a separate narrow-band command channel. The first terminal desiring a connection with the second terminal should then first exchange information with the base station via the narrow-band channel, which information comprises, for instance, the identity of the first terminal and/or the identity of the second terminal as well as information relating to the connection to be established itself. When thus via the narrow-hand channel the necessary information has been exchanged with the base station, the first terminal can establish a wide-band connection. Such connection can then be made, for instance, with the second terminal. For the purpose of communication via the narrow-band channel and the wide-band connection, the first terminal will generally be provided with different transmitting and receiving systems. In particular, the second terminal is identical to the first terminal.
A disadvantage of such a system is that it is rather costly. This is caused by the fact that the terminals are provided with double transmission systems, whereby, as stated, the first transmission system is used for establishing a narrow-band connection with the base station, while the second transmission system is used for establishing a wide-band connection with another terminal or terminals. In the case of a satellite system these connections are established via the satellite. The object of the invention is to provide a method and a system that can be made of simpler, better and more efficient design.
SUMMARY OF THE INVENTION
To that end, the method according to the invention is characterized in that the base station comprises a database with available frequencies and/or frequencies being in use for communication between terminals, and for establishing a connection via the satellite between the first and second terminal the system carries out the following steps:
1) the base station continuously transmits information to the satellite for establishing a connection, the information being transmitted on a reference and control carrier wave for retransmission by the satellite, and the information comprising at least the available frequencies and/or frequencies being in use for communication between terminals;
2) the first terminal receives the reference and control carrier wave retransmitted by the satellite, whereafter the received information is used for selecting at least one frequency available for communication, which selected frequency will be used for a desired connection with a particular terminal;
3) the first terminal transmits an operating carrier wave on the selected frequency to the satellite for retransmission by the satellite; and
4) the base station receives the operating carrier wave coming from the first terminal, retransmitted by the satellite, determines on the basis thereof that the selected frequency is in use, adjusts accordingly the database with available frequencies and/or frequencies being in use for communication between terminals, and adjusts accordingly the information about the available frequencies and/or frequencies being in use for communication between terminals that is transmitted on the reference and control carrier wave.
Surprisingly, in accordance with the invention, it is possible in a satellite system for the operating carrier wave which is normally used for maintaining the desired connection itself, to be used also for building up the connection. Here it is not required, as is the case in the prior art, for a terminal, before proceeding to transmit on the operating carrier wave, to ask the base station via a separate, often narrow-band channel for permission to proceed to transmit on the operating carrier wave. The communication equipment can thus be greatly simplified and improved and be made of an economically more advantageous design. Moreover, in this manner a connection can be established faster.
Because the base station continuously transmits information for establishing a connection, the first terminal can receive this information at any moment when it is desired that with the aid of the first terminal a connection with, for instance, the second terminal is established. Here the first terminal only needs to be provided with a single transmission system. The transmission from the first terminal to the base station of information about the frequency which the first terminal wishes to proceed to use also occurs via the same channel. In particular, the fact is even that to that end an operating carrier wave is transmitted by the first terminal on the selected frequency itself. Upon reception of the operating carrier wave by the base station, it can be determined on the basis of the frequency of the operating carrier wave that a terminal wishes to establish a connection on that frequency. Once this has been established by the base station, the base station can immediately adjust the database and, accordingly, the information which is transmitted on the reference and control carrier wave mentioned.
According to an advanced embodiment of the method according to the invention, the system further traverses the following steps:
5) the first terminal transmits on the operating carrier wave the identity of at least the second terminal to the satellite;
6) the base station, after reception of the operating carrier wave retransmitted by the satellite, determines the identity of the second terminal;
7) the base station transmits via the reference and control carrier wave the identity of the second terminal as well as setting parameters for the second terminal to the satellite;
8) the second terminal receives the reference and control carrier wave retransmitted by the satellite, recognizes its own identity and proceeds to self-setting on the basis of the received setting parameters for receiving via the satellite the operating carrier wave, which can comprise audio/video or other information, transmitted by the first terminal.
Because presently also the identity of terminals is transmitted with which the first terminal wishes to establish a connection, the base station can set these terminals accordingly via the reference and control carrier wave. The setting parameters to be transmitted in this connection can relate, for instance, to the type of signal that will be transmitted, such as digital audio or digital video, to bit rate, to the selected frequency, and to other parameters through which in these terminals elements such as downconverters, modulators, demodulators and multiplexers can be set.
In particular, the base station, after establishing the identity of the second terminal in step (
Gantt Alan
Hunter Daniel S.
I.G.P. B.V.
Jacobson Price Holman & Stern PLLC
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