Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-07-13
2001-08-21
Hunter, Daniel (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S428000, C455S430000, C455S435100, C455S440000
Reexamination Certificate
active
06278876
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to cellular and satellite communications. More particularly, the invention relates to a method and a system for implementing terminal to terminal connections via a geosynchronous earth orbit satellite in a satellite communication network.
Background and Description of Related Art
A mobile satellite communication system such as the Geosynchronous Earth Orbit Mobile (GEM) network discussed herein, typically includes one or more satellites, at least one fixed ground terminal such as a gateway system (GS) and several mobile access terminals (ATs). The access terminals typically communicate with the public switched telephone network (PSTN) or other mobile terminals via an air communication interface between the satellite and the gateway. Using the mobile access terminals, the satellite system provides a variety of telephony services. Satellite telephony systems as described herein share call processing information with terrestrial systems such as the GSM cellular system to allow compatibility between the satellite, cellular, and the public switch telephone network services. The terrestrial standards such as GSM may not apply directly to the mobile satellite communication system, more particularly the satellite air interface poses physical constraints not accounted for in the GSM architecture.
A number of communication systems utilizing satellites and small mobile terminals provide voice and other information communication. In such systems, the single-hop one way propagation delay is about 270 ms. This is about at the limit of acceptability for most users. If a call is established between two such users with two satellite hops, the one way delay becomes approximately 540 ms, which is generally unacceptable. In order to reduce this propagation delay when two mobile users are conversing, it would be desirable to provide a link made to establish a connection through the satellite, such that the connection involves only a single satellite hop.
Thus, there exists a need for a method and a system for performing satellite switched communications to enable the GEM network to establish a single hop satellite link between two user access terminals.
SUMMARY OF THE INVENTION
Accordingly, the present invention addresses a scheme for the establishment of single-hop terminal to terminal (TtT) call in the GEM network with the assignment of the terminal to terminal channel (TTCH) to allow the network and AT to have a reliable communication link via the satellite.
Briefly summarized, the present invention relates a system and method for implementing single hop space segment terminal to terminal connections. The system includes a satellite-based radio frequency (RF) communication link for conveying multiple communication channels over the space segment via one or more spot beams. A terrestrial supervisory transceiver such as a gateway station is provided in communication with the satellite-based communication link. Mobile hand-held terminals (HHTs), herein first and second access terminals, may be located within one or more of the spot beams to communicate with one another via a single hop connection through a satellite of the system. A switch is provided for communication switching with the satellite of the system for the multiple communication channels to couple the first access terminal and the second access terminal over the space segment via one or more of the spot beams. The terrestrial supervisory transceiver or gateway is provided in communication with the satellite switch via the satellite-based communication link for implementing the single hop space segment terminal to terminal connection.
It will be understood that both the foregoing and general description in the following detailed description are exemplary and intended to provide further explanation of the invention as claimed. The accompanying drawings provide an understanding of the invention as described in the preferred embodiments to illustrate the invention and serve to explain the principles of the invention.
REFERENCES:
patent: 5689568 (1997-11-01), Laborde
patent: 5765098 (1998-06-01), Bella
patent: 5781540 (1998-07-01), Malcolm et al.
patent: 5790939 (1998-08-01), Malcolm et al.
patent: 5812545 (1998-09-01), Liebowitz
Joshi Chandra
Noerpel Anthony
Roos David
Stelzer Gerard
Su Chi-Jiun
Hughes Electronics Corporation
Hunter Daniel
Sales Michael W.
Whelan John T.
Woldetatios Yemane
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