Northrop Grumman Systems Corporation

Trw Limited

Hughes Electronics Corporation

Comstream Corporation

David A Wright

Gregory S Caso

Stuart T Linsky

Reginald Jue

Dominic P Carrozza

Donald C Wilcoxson

Vincent C Moretti

Dennis A Nivens

Eldad Perahia

Michael W Mann

Aaron D Falk

Rhon L Williams

Michael S Munoz

Scott A Cooper

Itzhak Gurantz

Scott Adam Stephens

Jaime L Prieto, Jr

Gefferie H Yee-Madera

James E Justiss

Esmaell Yousefi

Mark E Bever

Scott L Wilkinson

Jean Tsao

The present invention provides a method () for virtual path switching of an ATM cell on a processing communications satellite. The method includes establishing a set of VPIs () associated with output ports on the satellite and assigning one VPI to an ATM cell (). The ATM cell may then be received by an input port of the satellite (). An associated output port () for the ATM cell is determined from the VPI, and the ATM cell is transferred to that output port (). The present invention may also provide for multicast switching (). The VPI assigned to the ATM cell may be associated with a multicast output port. The ATM cells may be reproduced () and reassigned with a new VPI from a multicast group of VPIs (). The reproduced cells are received at an input port of the satellite () for routing to the corresponding output ports.

Virtual path asynchronous transfer mode switching in a processing satellite communications system

A frame signal () for communicating payloads () of data includes a first payload field () and a first header field () with a first frame type indicator (). The frame signal () also includes a second payload field () and a second header field () smaller than the first header field () that includes a second frame type indicator (). The first payload field (), first header field (), second payload field (), and the second header field () are encapsulated in a single frame () to provide multiple payload delivery with reduced overhead compared to individually transmitted single payload frames.

Downlink beam hopping waveform

The invention is a receiver and a method of receiving data having a preferred application in a satellite receiver in accordance with the invention includes a memory () including an addressable storage array which stores a sequence of data samples contained in a time division multiplexed signal from a plurality channels (X, Y and Z) and outputs the stored data samples in a sequence of data groups with each data group containing a plurality of samples from one of the plurality of channels; and a decoder (), responsive to the data groups, which decodes the data samples within the data groups and outputs decoded data samples.

Buffering and sequencing of soft decisions of multiple channels into a single shared biorthogonal decoder

A method and apparatus for communicating fixed-length data packets through an intermediate computer network. The method comprises receiving a data packet characterized by a fixed-length packet format, and constructing a remnant packet characterized by the fixed-length packet format, which includes inserting at least a portion of the data packet routing information in the data field of the remnant packet. The method also comprises communicating the remnant packet, receiving the remnant packet and constructing a reconstructed data packet, which includes Inserting data packet routing information obtained from the remnant packet in the address field of the reconstructed packet. The apparatus comprises a communication network node comprising a receiver, transmitter, computer memory and processor for performing the foregoing method steps.

Encapsulation method and apparatus for communicating fixed-length data packets through an intermediate network

The present invention provides a highly accurate synchronization method for a satellite communication system (). The system maintains a downlink symbol counter at an earth terminal and determines a downlink symbol count representative of the time of arrival of a burst transmitted from the earth terminal to a satellite (). The earth terminal adjusts the downlink symbol counter to correspond to the downlink symbol count () upon arrival of a predetermined reference point in a downlink frame. A timing error may initially be determined by launching an entry order wire from the earth terminal to the satellite (). The timing error may be transmitted to the earth terminal using a correction code which indicates the transmission is early, late, absent, or no change is required (). The terminal may make additional periodic timing adjustments based on the length of the propagation path between the earth terminal and the satellite (). The earth terminal may then precisely time the transmission of bursts from the earth terminal to the satellite (). The length of the propagation path and the timing error may be stored in the earth terminal so that the earth terminal may reenter the system without undertaking multiple commissioning processes.

Synchronization method for a processing communication satellite

A method and apparatus for closed-loop power threshold leveling for a satellite communication system is provided. A preferred embodiment of the present invention includes a user earth terminal (UET) ( ), a satellite ( ) and a network control center (NCC) ( ). The satellite ( ) periodically determines an average error rate for data bursts transmitted by a plurality of UETs ( ) and sends the average error rate as well as the number of transmitted data bursts to the NCC ( ). The NCC ( ) accumulates average error rates over a period of time, and when a predetermined number of data bursts has been surpassed, determines an uplink power threshold adjustment based on the average error rates. The NCC ( ) then transmits the uplink power threshold adjustment to the satellite ( ), which adjusts an on-board uplink power level threshold in response to the uplink power threshold adjustment. In systems using multiple beams, the satellite ( ) maintains a separate uplink power level threshold for each beam, and determines a separate average error rate for each beam. The NCC ( ) then determines and transmits a separate uplink power threshold adjustment for each beam. In systems using multiple coding levels, the satellite ( ) determines separate error rates for each coding level, and the NCC ( ) determines uplink power offset adjustment corresponding to each coding level. The NCC ( ) then delivers the uplink power offset adjustments to the UETs ( ), which update their local power offset values stored in memory.

Satellite communication system threshold leveling techniques

A method and apparatus for closed-loop power threshold leveling for a satellite communication system. An aspect of the present invention includes a plurality of user earth terminals (UET), a satellite and a network control center (NCC). The NCC polls the UETs to obtain power profile information. When polled, the UELTs form power profile responses and send the responses back to the NCC. The NCC forms a power profile database and statistically analyzes the power profile information to determine an uplink power threshold adjustment. The NCC transmits the uplink power threshold adjustment to the satellite, which adjusts an on-board uplink power level threshold in response to the uplink power threshold adjustment. In systems using mutltiple coding levels, the NCC determines uplink power offset values corresponding to the individual coding levels. The NCC delivers the uplink power offset values to the UETs which update their local power offset values.

Method and apparatus for controlling a transmission power threshold of a satellite communication system

The present invention provides a method and apparatus for arbitration among the inputs of a crossbar cell switch. The input cells of the crossbar cell switch are stored at their respective input ports in input queues prior to switching. The first cell of each input queue is known as the Head of Line (HoL) cell. For each set of HoL cells that may be directed to a specific output port, the HoL cell with the largest input port queue size is assigned to be switched during the current switching epoch. The method and apparatus for arbitration allows the crossbar cell switch to operate with smaller input queues, increasing the throughput of the switch and minimizing both the transit delay for the data cells through the switch and the buffer size needed to accommodate input queues.

Queue size arbitration method and apparatus to enhance performance of crossbar cell switch

A method and apparatus for mitigation of false co-channel uplink reception, also known as show-thru, in an uplink A due to an uplink B at a satellite receiver. The method includes storing multiple scrambling sequences associated with respective individual uplinks, including a scrambling sequence A, receiving uplink A signals at an uplink A receiver, applying scrambling sequence A to the uplink A signals to generate descrambled A data, and then decoding the descrambled A data. The decoding step includes the generation of a decoder failure signal in the event that decoding is unsuccessful, and the method discards the descrambled A data if the decoder failure signal is asserted. Therefore, any show-thru data derived from uplink B will be discarded in the uplink A receiver, and vice versa. The step of applying the scrambling sequence may be effected using an exclusive-or operation.

Mitigation of false co-channel uplink reception in a processing satellite communication system using scrambling sequences

A downlink orderwire integrator ( ) and separator ( ) for use in a processing satellite ( ) and a user terminal ( ) in a satellite based communications system ( ) is provided having a formatter ( ), a cell switch ( ) and a cell sieve ( ). The formatter ( ) generates orderwire cells ( ) with each orderwire cell ( ) having a header ( ) and a body ( ). The cell switch ( ) receives the orderwire cells ( ) from the formatter ( ) and traffic cells ( ) from at least one uplink ( ) and arranges the orderwire cells ( ) and the traffic cells ( ) in at least one frame ( ) to transmit on at least one downlink ( ). The frame ( ) includes a fixed custom frame portion ( ) and a fixed traffic portion ( ) that contains both the traffic cells ( ) and the orderwire cells ( ). The cell sieve ( ) receives at least one frame ( ) from the at least one downlink ( ) and separates the traffic cells ( ) and the orderwire cells ( ) from the traffic portion ( ), such that the formatter ( ) and cell switch ( ) are positioned within the processing satellite ( ) and the cell sieve ( ) is positioned within the user terminal ( ).

Downlink orderwire integrator and separator for use in a satellite based communications system

An initial entry processor ( ) for use in a processing satellite ( ) in a satellite based communications system ( ) is provided having a buffer ( ), a detection and timing circuit ( ) and an identity circuit ( ). The buffer ( ) stores an initial entry burst ( ) transmitted from at least one terrestrial terminal ( ) to the processing satellite ( ). The detection and timing circuit ( ) detects the initial entry burst ( ) and determines a time of arrival of the initial entry burst ( ) relative to an initial entry burst slot ( ). The identity circuit ( ) determines an identity of the terrestrial terminal ( ) that transmitted the initial entry burst ( ) such that the time of arrival is used by the identified terrestrial terminal ( ) during subsequent communications with the processing satellite ( ).

Onboard initial entry processor for facilitating a satellite communication

The present invention provides a comprehensive method for controlling, independently, transmit power and coding levels for data transmitted in uplinks and downlinks. One preferred embodiment of the present invention provides a method for adaptive coding of data in a downlink. A data error rate associated with downlink data (e.g., a character error rate provided by a Reed Solomon decoder) is determined. The method, based upon pre-established error rate thresholds, controls the level of coding (e.g., heavy or light) on data in the downlink to achieve a desired data error rate. Heavy coded data is typically associated with a code rate half that of light coded data, and changes between heavy and light coding may be selected using a destination address applied at an originating terminal and interpreted at the satellite.

Adaptive coding scheme for a processing communications satellite

A distributed demand assigned multiple access control scheme for use in connection with a processing satellite communications system, where multiple users are assigned to a common transmission resource as part of a sharing set. The control scheme of the invention makes use of a reservation procedure by transmitting set addressed reservation messages in a contentious control flow to reserve data transfer time in a non-contentious main flow. Each user of the sharing set is synchronized to the next available uplink time slot available to transmit data in the main flow. If a transmitted reservation message is returned in the satellite downlink, the terminal knows that all of the users of the set received the message. That reserved time interval in the main flow Is now owned by that user, and each user in the shared set updates its next available uplink time slot based on the reserved time.

Distributed control DAMA protocol for use with a processing communications satellite

The present invention is a demodulator and a method of demodulating burst communications. A demodulator ( ) includes a phase angle source ( ), coupled to a current received burst communication, which provides a phase angle of the current received burst communication; a comparator ( ), coupled to the phase angle source and a source of an estimated phase angle, which provides an output signal representing an angular difference between a phase of the current received burst communication and the estimated phase angle; and a phase lock loop ( ), coupled to the output signal, which provides the estimated phase angle. The phase lock loop includes a Doppler accumulator ( ) which provides a Doppler output which provides compensation in the estimated phase angle for the Doppler effect produced by relative motion between the demodulator and a source of the burst communications.

Doppler learning phase lock loop for burst demodulator

The present invention relates to distributed ATM switches for use within an ATM network including processing satellite links. The functionality of the distributed ATM switch is preferably performed at three distinct locations. The first location is at a user earth terminal configured to perform at least one user plane function. The second location is at a network operations center configured to perform at least one control plane function. Finally, the remaining ATM switch functionality is performed within the payload of a processing satellite.

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Solana Beach, CA, United States of America

David A Wright