Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
1999-01-25
2001-05-29
Nguyen, Chau (Department: 2663)
Multiplex communications
Communication over free space
Repeater
C370S395430, C370S414000
Reexamination Certificate
active
06240075
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to data cell processing in a satellite communication system and more particularly relates to routing arbitration of such cells.
Weight and power are critical parameters when designing for space-based data cell routing where higher weight and power translate to higher spacecraft and launch costs and/or reduced capacity which would lower potential revenue.
A non-blocking routing switch with multiple input and output ports has significant power and weight advantages over bus or banyan type architectures, and such a switch requires some form of arbitration. Since all input sources to such a switch are independent, the multiple input ports may attempt to send data to the same output port at the same instant. Arbitration is required to resolve this potential conflict.
A terrestrial routing switch can include sophisticated arbitration algorithms executed on a high power computer. However, due to weight/power limitations on a spacecraft, such approaches are impractical, and there is a need for a low power solution which can arbitrate between data cells contending for the same node or port. The solution must be able to arbitrate in the time required to route a data cell aboard the satellite.
BRIEF SUMMARY OF THE INVENTION
One object of the invention is to provide arbitration in connection with the switching of data cells between input and output nodes suitable for use in a communication satellite.
Another object of the invention is to provide a cell switching arbitration capability which can select a single cell out of a group for data cells having the same destination priority and other decision factors in a fair manner.
Still another object of the invention is to provide a cell switching arbitration capability of the foregoing type which requires a minimum number of integrated circuit pins.
Yet another object of the invention is to provide a cell switching arbitration capability of the foregoing type capable of using serial transmission of data.
The preferred embodiment of the present invention is useful for data cell switching arbitration in a communication satellite. Data cells are stored with corresponding routing codes and corresponding decision factor codes, preferably in a buffer memory. A unique arbitration code is assigned to each cell being submitted to arbitration. The decision factor codes corresponding to like routing codes are compared, and, in the event the compared decision factor codes are identical, the unique arbitration codes associated with the compared decision factor codes are compared. The data cell corresponding to one of the compared unique arbitration codes is then selected and transmitted, preferably along a transmission path, such as a cross connect switch. As a result, it is ensured that exactly one cell is selected corresponding to a given routing code and fairness can be achieved through a pseudo-random assignment of unique routing codes.
The foregoing techniques enable a low power implementation for centralized arbitration which accommodates multiple decision factors. The techniques enable lower power and lower weight circuitry which results in higher capacity and/or lower cost. By using the preferred embodiment of the invention, the speed of arbitration is increased and the data throughput is maximized. The invention also enables serial transmission of decision information which minimizes input/output requirements and the requisite number of pin connectors, resulting in lower weight.
REFERENCES:
patent: 5530902 (1996-06-01), McRoberts et al.
patent: 5805816 (1998-09-01), Picazo, Jr. et al.
patent: 6002675 (1999-12-01), Ben-Michael et al.
Gregoire Darren R.
Takahashi Scott M.
Wong Roland Y.
Nguyen Chau
Thousand Connie M.
Trinh D.
TRW Inc.
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